Iwate University

Professor Hiroyuki Fujishiro

Research Achievements（1990 ~ 2022）

March 2022

目次
１．代表的研究の概略…………………………………………………………………………………………… 1
２．学術論文 291 編

A. CMR 効果を示す Mn, Co 酸化物の熱物性 49 編 ………………………………………………… 3
B. 酸化物超電導体の熱物性 30 編 …………………………………………………………………… 6
C. 超伝導線材、シース合金材料の熱物性 13 編 …………………………………………………… 8
D. 熱物性測定技術の開発 6 編 ………………………………………………………………………… 9
E. REBaCuO 系超電導バルクの熱物性 12 編 ……………………………………………………… 9
F. REBaCuO 系超電導バルク磁石の開発 59 編……………………………………………………… 10
G. 超電導バルク磁石の着磁シミュレーション 32 編 ……………………………………………… 14
H. ハイブリッド型超電導バルク磁石の開発 10 編 ………………………………………………… 16
I. MgB2 超電導バルク磁石の開発 29 編 ……………………………………………………………… 17
J. 熱電変換材料の開発 10 編 ………………………………………………………………………… 19
K. 高分子材料、磁性蓄冷材、その他の熱物性 9 編 ………………………………………………… 20
L. パーコレーション伝導、熱伝導率のモデル解析 4 編 …………………………………………… 21
M. 多層膜超伝導体の研究 18 編 ……………………………………………………………………… 21
N. Si, GaAs, ZnSe などの半導体材料に関する研究 11 編 ………………………………………… 22
O. 博士学位論文 ………………………………………………………………………………………… 23
３．代表的論文リスト 10 編 …………………………………………………………………………………… 24
４．研究論文の分析、概要……………………………………………………………………………………… 25
５．国際会議報告論文 12 編 …………………………………………………………………………………… 30
６．著書 3 編 …………………………………………………………………………………………………… 32
７．解説・総説 9 件、新聞記事１件 ………………………………………………………………………… 33
８．特許出願 10 件、特許取得 3 件 …………………………………………………………………………… 34
９．表彰・受賞 4 件 …………………………………………………………………………………………… 36

10．国際会議出席発表（海外での発表 40 件、国内での発表 27 件）……………………………………… 37
11．外部資金獲得（代表者のみ）（科研費 6 件、奨励金 17 件）…………………………………………… 43
12．研究室の卒論、修論、博論の題目（平成 3 年度〜令和 3 年度）……………………………………… 46

13．担当した講義 ……………………………………………………………………………………………… 55
14．略歴 ………………………………………………………………………………………………………… 56
15．研究生活の振り返りと謝辞 ……………………………………………………………………………… 57
付録

A: 最終講義予定スライド ……………………………………………………………………………………… 59
B: 代表的論文 10 編 …………………………………………………………………………………………… 68
1)「低温における熱拡散率と熱伝導率の同一セッティング測定」
低温工学 28 (1993) pp. 533-539 (D-1) (No. 10 paper) ……………………………………………… 70

2) “Higher trapped ﬁeld over 5 Tesla on HTSC bulk by modiﬁed pulse ﬁeld magnetizing”,

Physica C 445-448 (2006) pp. 334-338 (F-17) (No. 134 paper) …………………………………… 78
3) “Simulation of temperature and magnetic ﬁeld distribution in superconducting bulk
during pulsed ﬁeld magnetization”,

Supercond. Sci. Technol. 23 (2010) 105021 (G-1) (No. 174 paper) ………………………………… 84
4) “Valence shift of Pr ion from 3+ to 4+ in (Pr1-yYy)0.7Ca0.3CoO3 estimated by X-ray
absorption spectroscopy”

J. Phys. Soc. Jpn. 81 (2012) 064709 (A-41) (No. 189 paper) ……………………………………… 93
5) “Electrical resistivity anomaly in (Pr1-yMy)1-xCaxCoO3 epitaxial ﬁlms (M = Y, Gd) fabricatedby pulsed laser deposition”

AIP Advances 6 (2016) 025318 (A-48) (No. 232 paper) …………………………………………… 99
6) “A new concept of hybrid trapped ﬁeld magnet lens (HTFML)”

Supercond. Sci. Technol. 31 (2018) 044005 (H-1) (No. 257 paper) ……………………………… 109
7) “Experimental realization of a Hybrid Trapped Field Magnet Lens (HTFML) using a
GdBaCuO magnetic lens and MgB2 bulk cylinder”

Supercond. Sci. Technol. Letter 32 (2019) 12LT03 (H-3) (No. 271 paper) ……………………… 119
8) “A record-high trapped ﬁeld of 1.61 T in MgB2 bulk comprised of copper plates and soft ironyoke cylinder using pulsed-ﬁeld magnetization”

Supercond. Sci. Technol. 33 (2020) 085002 (I-25) (No. 276 paper)…………………………… 127

9) “A conceptual study of a high gradient trapped ﬁeld magnet (HG-TFM) providing toward a quasizero gravity space on Earth”

Supercond. Sci. Technol. 34 (2021) 035001 (H-8) (No. 283 paper) ……………………………… 13810)“Experimental realization of an all-(RE)BaCuO hybrid trapped ﬁeld magnet lens generating a 9.8 T
concentrated magnetic ﬁeld from a 7 T external ﬁeld”

Supercond. Sci. Technol. 34 (2021) 05LT02 (H-9) (No. 284 paper) …………………………… 152
C: 動画

・2013 年研究室紹介
・2020 年 JST イノベーションジャパン シーズ紹介
・モーゼ効果のデモンストレーション

D: ホームページのイメージ※添付の DVD には全てのデータ、論文ファイル、動画等が掲載されている。

１．代表的研究の概略
１．酸化物超電導体の熱的性質（熱伝導率、熱拡散率、⾳速、熱膨張、熱起電⼒）に関する研究

1993 年に能登宏七教授と共同で He 冷凍機を⽤いた低温における熱伝導率の完全⾃動測定装置を開発し、様々な条件で作製した酸化物超伝導体の熱伝導率を測定し、フォノン散乱機構の解明を⾏った。さらに、オリジナルな熱拡散率測定法、ストレインゲージを⽤いた熱膨張測定法、熱起電⼒測定法、2 次元熱伝導率測定法、接触熱抵抗測定法等を開発した。10 T までの磁場中における超電導線材や超電導バルク材の熱物性の測定を系統的に⾏った。超電導バルク材に関する⼀連の研究は、⽂部省の岩⼿県地域結集型共同研究事業「⽣活・地域への磁気活⽤技術の開発」(1999~2004)で実施
され、研究成果は論⽂発表すると共に、データベースを構築して Web 公開を継続して⾏っている。
２．Mn, Co 系酸化物の熱的、電気的特性に関する研究

1997 年頃から、超巨⼤磁気抵抗(CMR)効果を⽰す様々な Mn 系酸化物(RE1-xAExMnO3)や、⼤きな
熱的、熱起電⼒を有し熱電変換材料への応⽤が期待される Co 系酸化物(RE1-xAExCoO3)の作製及び、電気的特性の研究を実施した。磁性転移付近における熱的散乱の変化や、磁場中熱伝導率測定、⾳速測定（東北⼤⾦属材料研究所深瀬研究室との共同研究）を⾏い、論⽂発表を⾏った。これらの研究の⼀部はチェコ科学アカデミー物理学研究所の J. Hejtmanek 博⼠と共同で実施した。
３．Co 系酸化物(Pr1-yYy)1-xCaxCoO3 の特異な⾦属絶縁体転移に関する研究

2005 年頃から、特異な⾦属絶縁体転移を⽰す Co 系酸化物(Pr1-yYy)1-xCaxCoO3 (PYCCO)に注⽬し、焼結体試料作製と電気的、熱的測定等を⾏った。2011 年からは Pr イオンの転移点近傍での価数変化を測定するため、SPring-8 での XAFS 測定を⾏い、Pr イオン価数変化と関係する転移メカニズムを明らかにした。さらに 2015 年から、レーザ蒸着法（PLD 法）による PYCCO 単結晶薄膜を作製し（東北⼤⾦属材料研究所後藤研究室との共同研究）、多結晶に対する結果との⽐較検討を⾏った。
⼀連の研究はチェコ科学アカデミー物理学研究所の J. Hejtmanek 博⼠と共同で実施した。
４．超電導バルク材のパルス着磁法の実験的研究

2002 年頃から、⽂部省の岩⼿県地域結集型共同研究事業(1999~2004)の中で、安価で簡便な着磁法であるパルス着磁法(PFM)により REBaCuO 系超電導バルク材の着磁研究を実験的に⾏い、特に着磁時の温度測定の重要性に注⽬して研究を実施した。実験結果の蓄積から、2005 年に温度上昇を低減した Modified Multi-Pulse Technique with Stepwise Cooling (MMPSC)法を提案し、直径 45 mm の
GdBaCuO バルク表⾯で PFM 法では世界最⾼となる 5.2 T の捕捉磁場を実現した。この記録は現在も破られていない。現在でも PFM 法による捕捉磁場の向上の⼿法として、MMPSC 法（⼜は Twostep MPSC 法）が⼀般に⽤いられている。さらに、MgB2 バルクに対しても PFM 法を⽤いて捕捉磁場の向上を⽬指した。その結果、2016 年に単⼀パルスにより 1.1 T を達成し、さらに 2019 年にはMgB2 バルク、Cu 板、軟磁鉄ヨークの複合体に複数パルス磁場印加により 1.6 T の世界最⾼の捕捉
磁場を実現した。これらの⼀連の研究は、 (株)イムラ材料開発研究所（現：(株)イムラジャパン）、(株)新⽇本製鐵（現：(株)⽇本製鉄）、理化学研究所及び、イタリア EDISON S.p.A., R&D Division のGiovanni Giunchi 博⼠及び、英国ケンブリッジ⼤学 Mark D. Ainslie 博⼠との共同研究で実施した。
－1－

５．超電導バルク材の着磁現象のシミュレーション

実験による検討は限られたパラメータを変化させるに過ぎず、実験結果の再現や新たなパルス着磁法の提案を⾏うために、2010 年頃から有限要素法を⽤いた PFM の電磁気的、熱的シミュレーシ
ョンを⾏った。シミュレーションの結果は PFM 現象を理解する上で⾮常に重要であることを明らかにした。さらに応⼒解析に関するシミュレーションを追加し、超電導バルクの着磁時の破壊を回避するための機械的補強法の提案を⾏った。実験とシミュレーションを併⽤した着磁プロセスの研
究は他の研究機関では⾏われて居らず、多くの論⽂の出版と国際会議での招待講演が⾏われた。これらの⼀連の研究は、英国ケンブリッジ⼤学 Mark D. Ainslie 博⼠との共同研究で実施した。
６．新しい超電導バルク磁⽯の提案と実証
これまでの超伝導バルクの着磁に関する実験とシミュレーションの多くの蓄積から、全く新しい

バルク磁⽯装置を２件提案し特許出願を⾏った。１つは 2017 年に発明した着磁磁場よりも⼤きな
捕捉磁場を持続的に発⽣するハイブリッド型超伝導バルク磁⽯レンズ(HTFML: Hybrid Trapped Field
Magnet Lens)であり、実際に GdBaCuO バルクレンズと GdBaCuO バルク円筒を⽤いて，着磁磁場 7
T で 9.8 T の捕捉磁場を持続的に発⽣することを実験で確認した。もう⼀つは 2020 年に発明した
HTFML よりも⾮常に⼤きな勾配磁場を発⽣する新しいタイプのバルク磁⽯（HG-TFM: High
Gradient Trapped Field Magnet）である。HG-TFM は着磁磁場 8.5 T で着磁した結果，磁気⼒場 B zdBz/dz= 1930 T2/m が実現し、この擬似微⼩重⼒環境において反磁性体である⾦属ビスマスや⽔滴の浮上を確認した。HG-TFM

は今後、地上で擬似微⼩重⼒環境の実現を可能にし、ライフサイエンス分野への応⽤展開が可能である。これらの⼀連の研究は、大学院生の高橋圭太君（現：学習院大学助教）と英国ケンブリッジ⼤学 Mark D. Ainslie 博⼠との共同研究で実施した。
７．新しい酸化物系熱電変換材料に関する研究

これまで蓄積してきた酸化物試料作製と熱伝導率や熱起電⼒等の熱物性測定の経験を⽣かし、2003 年頃から様々な新しい酸化物材料の熱電変換特性を検討した。具体的に検討した材料は、RE1、CuO 系、TiO2xAExCoO3 系（チェコ科学アカデミー物理学研究所の J. Hejtmanek 博⼠と共同研究）
系、In2O3-SnO2 系、BiCuSeO 系（東北⼤⾦属材料研究所後藤研究室との共同研究）、LiyCoO2 系、
NayCoO2 系、SnSe 単結晶薄膜（東北⼤⾦属材料研究所後藤研究室との共同研究）などである。各材
料の熱電材料としてのポテンシャルを明らかにした。

－2－２．学術論⽂ 291 編
A. Mn, Co 酸化物の熱物性（熱伝導率、熱拡散率、熱膨張、⾳速、熱起電⼒） 49 編
(A-1) M. Ikebe, H. Fujishiro and Y. Konno, “Anomalous Phonon-Spin Scattering in La1-XSrXMnO3”,
J. Phys. Soc. Jpn. 67 (1998) pp. 1083-1085 (No. 51 paper)(A-2) H. Fujishiro, M. Ikebe and Y. Konno, “Phase Transition to Antiferromagnetic State in La1-XSrXMnO3(X ≥ 0.5)”,
J. Phys. Soc. Jpn. 67 (1998) pp. 1799-1800 (No. 52 paper)(A-3) H. Fujishiro, T. Fukase and M. Ikebe, “Charge Ordering and Sound Velocity Anomaly in La1-XSrXMnO3(X ≥ 0.5)”,
J. Phys. Soc. Jpn. 67 (1998) pp. 2582-2585 (No. 53 paper)(A-4) H. Fujishiro and M. Ikebe, “Two-level-like anomalous phonon scattering in La1-XSrXMnO3 andLa2-XSrXCuO4”,
Physica B 263-264 (1999) pp. 691-694 (No. 56 paper)(A-5) H. Fujishiro, T. Fukase, M. Ikebe and T. Kikuchi, “Sound Velocity Anomaly at around X~1/8 in
La1-XCaXMnO3”,
J. Phys. Soc. Jpn. 68 (1999) pp. 1469-1472 (No. 57 paper)(A-6) H. Fujishiro, M. Ikebe, T. Kikuchi and H. Ozawa, “First-order-like ferromagnetic transition in(La1-yPry)1-x(Ca1-zSrz)xMnO3 (X~0.25)”,
Physica B 281&282 (2000) pp. 491-493 (No. 65 paper)(A-7) M. Ikebe, H. Fujishiro and S. Sugawara, “An evidence for strong phonon-conduction electron interaction
from thermal transport anomaly in Nd0.50Sr0.50MnO3”,
Physica B 281&282 (2000) pp. 496-497 (No. 66 paper)(A-8) H. Fujishiro, M. Ikebe, S. Ohshiden and K. Noto, “Canted Antiferromagnetic Order and Large
Magnetoresistance in La1-XCaXMnO3, Pr1-XCaXMnO3 and other RE1-XAEXMnO3 Manganese Oxides(X~0.9)”,J. Phys. Soc. Jpn. 69 (2000) pp. 1865-1871 (No. 69 paper)(A-9) H. Fujishiro, S. Ohshiden and M. Ikebe, “Thermal Transport Anomaly Associated with Weak
Ferromagnetism in CaMnO3”,
J. Phys. Soc. Jpn. 69 (2000) pp. 2082-2086 (No. 70 paper)(A-10) H. Fujishiro, T. Fukase and M. Ikebe, “Anomalous Lattice Softening at X=0.19 and 0.82 in
La1-XCaXMnO3”,
J. Phys. Soc. Jpn. 70 (2001) pp. 628-631 (No. 73 paper)(A-11) M. Ikebe, H. Fujishiro, S. Kanoh and T. Mikami, “Characteristic Phonon Scattering Enhancement
Correlated with Magnetic and Charge Orders in La1-XSrXMnO3 (X > 0.50)”,
phys. stat. sol. (b) 225 (2001) pp. 135-143 (No. 74 paper)(A-12) H. Fujishiro, S. Kanoh, H. Yamazaki and M. Ikebe, “Enhanced Phonon Heat Conduction Correlated with
Induced Ferromagnetic Metallic Phase in Pr0.65Ca0.35(Mn1-ZCoZ)O3”,
J. Phys. Soc. Jpn. 70 (2001) pp. 2616-2621 (No. 75 paper)(A-13) Y. Moritomo, T. Akimoto, H. Fujishiro and A. Nakamura, “Specific heat of La1-XSrXMnO3 (X~0.5):
Comparison between three- and two-dimensional metallic states”,
Phys. Rev. B 64 (2001) pp. 064401-1~4 (No. 77 paper)(A-14) H. Fujishiro, “Thermal conductivity anomalies around antiferromagnetic order in La0.50Sr0.50MnO3 andNd0.50Sr0.50MnO3 crystals”,
Physica B 307 (2001) pp. 57-63 (No. 78 paper)
5－3－

(A-15) H. Fujishiro, S. Kanoh and M. Ikebe, “Heat Transport Enhancement in Ferromagnetic Metallic Phase of
La1-XBaXMnO3”,
J. Phys. Soc. Jpn. 71 (2002) Suppl. pp. 142-144 (No. 79 paper)(A-16) M. Ikebe, H. Fujishiro, H. Yamazaki and S. Kanoh, “Stabilization of Ferrromagnetic Metallic Phase andAnomalous Magnetotransport in Pr1-XCaX(Mn1-ZCoZ)O3”,
J. Phys. Soc. Jpn. 71 (2002) Suppl. pp. 145-147 (No. 80 paper)(A-17) H. Fujishiro, M. Ikebe, T. Akashi and T. Goto, “Thermal diffusivity of La1-XCaXMnO3 up to 1200 K”,
Physica B 316-317 (2002) pp.261-264 (No. 81 paper)(A-18) M. Ikebe, H. Fujishiro, and M. Numano, “Effect of oxygen content variation on phonon heat transport in
La0.75Ca0.25MnO3+d”,
Physica B 316-317 (2002) pp. 265-268 (No. 82 paper)(A-19) H. Fujishiro, S. Sugawara and M. Ikebe, “Anomalous phonon transport enhancement at first-orderferromagnetic transition in (Gd,Sm,Nd)0.55Sr0.45MnO3”,
Physica B 316-317 (2002) pp.331-334 (No. 83 paper)(A-20) H. FUJISHIRO, M. IKEBE, S. KANOH AND H. OZAWA, “THERMAL TRANSPORT IN
FERROMAGNETIC La1-XAEXMnO3 WITH LARGE DIVALENT IONS”,
ACTA PHYSICA POLONICA B 34 (2003) pp. 823-826 (No. 87 paper)(A-21) M. IKEBE, H. FUJISHIRO AND H. OZAWA, “EFFECT OF A-SITE CATION SIZE MISMATCH ON
FIRST-ORDER-LIKE FERROMAGNETIC TRANSITION IN PEROVSKITE MANGANITES”,
ACTA PHYSICA POLONICA B 34 (2003) pp. 827-830 (No. 88 paper)(A-22) K. Suzuki, H. Fujishiro, Y. Kashiwada, Y. Fujine and M. Ikebe, “Magnetic, electrical and thermal
properties of La0.80Sr0.20(MnyCo1-y)O3”,
Physica B 329-333 (2003) pp.922-923 (No. 91 paper)(A-23) Y. Kashiwada, H. Fujishiro and M. Ikebe, “Thermal conductivity of Pr0.65(Ca1-ZSrZ)0.35MnO3 under appliedfield”,
Physica B 329-333 (2003) pp. 924-925 (No. 92 paper)(A-24) Y. Watanabe, K. Takahashi, S. Awaji, K. Watanabe. H. Fujishiro and M. Ikebe, “Temperature and Magnetic
Field Dependence of the Coexistent Phases in La1-XCaXMnO3 (X=0.47, 0.49),
J. Phys. Soc. Jpn. 72 (2003) pp. 817-821 (No. 96 paper)(A-25) Y. Fujine, H. Fujishiro, K. Suzuki, Y. Kashiwada and M. Ikebe, “Magnetism and thermoelectricity in
La0.8Sr0.2Co1-ZMZO3 (M: 3d transition metal)”,J. Mag. Mag. Mat. 272-276 (2004) pp. 104-105 (No. 98 paper)(A-26) H. Fujishiro, Y. Fujine, Y. Mita and M. Ikebe, “Thermal conductivity and magnetism in (Ca1-XSrX)MnO3”,
J. Mag. Mag. Mat. 272-276 (2004) pp. 1796-1797 (No. 99 paper)(A-27) M. Ikebe, H. Fujishiro, S. Kanoh and H. Yamazaki, “Lattice effect on ferromagnetic-metal phase transitionin Pr0.65Ca0.35(Mn1-ZCoZ)O3 and Pr0.65Ca0.35(Mn1-ZCrZ)O3”,
J. Mag. Mag. Mat. 272-276 (2004) pp. 1798-1799 (No. 100 paper)(A-28) J. Hejtmanek, Z. Jirak, K. Knizek, M. Marysko, M. Veverka and H. Fujishiro, “Magnetism, structure andtransport of Y1-XCaXCoO3 and La1-XBaXCoO3”,
J. Mag. Mag. Mat. 272-276 (2004) pp. e283-e284 (No. 101 paper)(A-29) M. Ikebe, H. Fujishiro, T. Kumagai, A. Fujiwara and Y. Obi, “Magic d-electron number of doped ions foroccurrence of ferromagnetic metal phase in Pr0.65Ca0.35Mn0.96A0.04O3”,
Physica B 359-361 (2005) pp. 1294-1296 (No. 110 paper)(A-30) Y. Fujine, H. Fujishiro, Y. Kashiwada, J. Hejtmanek and M. Ikebe, “Anomalous phonon scattering by JahnTeller active Co intermediate spins in LaCoO3 and doped LaCoO3”,
Physica B 359-361 (2005) pp. 1360-1362 (No. 111 paper)

6－4－

(A-31) M. Ikebe, H. Fujishiro, S. Kanoh and T. Fukase, “Anomalies in Sound Velocity and Thermal Expansion
Related to Charge Order and Ferromagnetic Transitions in Pr0.65Ca0.35(Mn1-ZCoZ)O3”,
Physica B 378-380 (2006) pp. 534-535 (No. 123 paper)(A-32) H. Fujishiro, M. Ikebe, T. Kikuchi and T. Fukase, “Anomalous Sound Velocity Behavior of La1-XCaXMnO3(X~0.48) in Applied Field”,
Physica B 378-380 (2006) pp. 518-519 (No. 124 paper)(A-33) Y. Kashiwada, H. Fujishiro, Y. Fujine, M. Ikebe and J. Hejtmanek, “Metal-Insulator Transition and Phonon
Scattering Mechanisms in La1-XSrXCoO3”,
Physica B 378-380 (2006) pp. 529-531 (No. 125 paper)(A-34) H. Fujishiro and M. Ikebe, “Thermal Conductivity Anomaly in La0.52Ca0.48MnO3 under Applied Field”,
Physica B 378-380 (2006) pp. 499-500 (No. 128 paper)(A-35) H. Fujishiro, T. Naito, Y. Kashiwada and Y. Fujine, “Thermal conductivity anomalies of RECoO3 relatedwith spin-state transition”,
J. Phys. Soc. Jpn. 77 (2008) 084603 (5 pages) (No. 149 paper)(A-36) T. Naito, M. Sumomozawa, H. Sasaki and H. Fujishiro, “Thermal Conductivity of (Pr1-xREx)0.7Ca0.3CoO3(RE=Sm, Gd) around Metal-Insulator – Spin-state Transition”,
J. Phys. Conf. Series 150 (2009) 022062 (4 pages) (No. 155 paper)(A-37) T. Naito, H. Sasaki and H. Fujishiro, “Simultaneous metal-insulator and spin-state transition in(Pr1-yREy)1-xCaxCoO3 (RE=Nd, Sm, Gd, and Y)”,J. Phys. Soc. Jpn. 79 (2010) 034710 (5 pages) (No. 166 paper)(A-38) T. Naito, H. Sasaki, H. Fujishiro and M. Yoshizawa, “Elastic and Thermal Transport Properties of(Pr1-yGdy)0.7Ca0.3CoO3 at Metal Insulator Transition”,
J. Phys. Conf. Series 200 (2010) 012137 (4 pages) (No. 167 paper)(A-39) J. Hejtmanek, E. Santava, K. Knizek, M. Marysko, Z. Jirak, T. Naito, H. Sasaki, and H. Fujishiro, “Metalinsulator transition and the Pr3+/Pr4+ valence shift in (Pr1-yYy)0.7Ca0.3CoO3”,
Phys. Rev. B 82 (2010) 165107 (7 pages) (No. 175 paper)(A-40) M. Marysko, Z. Jirak, K. Knizek, P. Novak, J. Hejtmanek, T. Naito, H. Sasaki, and H. Fujishiro,“Thermally and field-driven spin-state transitions in (Pr1-yYy)0.7Ca0.3CoO3“
J. Appl. Phys. 109 (2011) 07E127 (3 pages) (No. 178 paper)(A-41) H. Fujishiro, T. Naito, S. Ogawa, K. Nitta, J. Hejtmanek, K. Knizek and Z. Jirak, “Valence shift of Pr ion
from 3+ to 4+ in (Pr1-yYy)0.7Ca0.3CoO3 estimated by X-ray absorption spectroscopy”,
J. Phys. Soc. Jpn. 81 (2012) 064709 (5 pages) (No. 189 paper)(A-42) H. Fujishiro, T. Naito, D. Takeda, N. Yoshida, T. Watanabe, K. Nitta, J. Hejtmanek, K. Knizek and Z.
Jirak, “Simultaneous valence shift of Pr and Tb ions at the spin-state transition in(Pr1-yTby)0.7Ca0.3CoO3”,
Phys. Rev. B 87 (2013) 155153 (7 pages) (No. 203 paper)(A-43) J. Hejtmánek, Z. Jirák, O. Kaman, K. Knížek, E. Santava, K. Nitta, T. Naito, and H. Fujishiro, “Phasetransition in Pr0.5Ca0.5CoO3 and related cobaltites”,
The European Physical Journal B 86 (2013) 305 (8 pages) (No. 204 paper)(A-44) Z. Jirak, J. Hejtmanek, K. Knizek, M. Marysko, P. Novak, E. Santava, T. Naito and H. Fujishiro, “Groundstate properties of the mixed-valence cobaltites Nd0.7Sr0.3CoO3, Nd0.7Ca0.3CoO3 and Pr0.7Ca0.3CoO3”,
J. Phys. Condensed Mater 25 (2013) 216006 (12 pages) (No. 208 paper)(A-45) K. Knizek, J. Hejtmanek, M. Marysko, P. Novak, E. Santava, Z. Jirak, T. Naito, H. Fujishiro and C. R. delaCruz, “Spin-state crossover and low-temperature magnetic state in yttrium doped Pr0.7Ca0.3CoO3”,
Phys. Rev. B 88 (2013) 224412 (8 pages) (No. 209 paper)(A-46) Z. Jirak, J. Hejtmanek, K. Knizek, P. Novak, E. Santava, and H. Fujishiro, “Magnetism of perovskite
cobaltites with Kramers rare-earth ions”,
J. Appl. Phys. 115 (2014) 17E118 (3 pages) (No. 210 paper)
7－5－

(A-47) T. Naito, H. Fujishiro, T. Nishizaki, N. Kobayashi, J. Hejtmanek, K. Knizek and Z. Jirak, “Suppression of
the metal-insulator transition by magnetic field in (Pr1-yYy)0.7Ca0.3CoO3 (y = 0.0625)”,
J. Appl. Phys. 115 (2014) 233914 (5 pages) (No. 213 paper)(A-48) Y. Noda, H. Fujishiro, T. Naito, A. Ito, T. Goto, J. Hejtmanek and Z. Jirak, “Electrical resistivity anomalyin (Pr1-yMy)1-xCaxCoO3 epitaxial films (M = Y, Gd) fabricated by pulsed laser deposition”,
AIP Advances 6 (2016) 025318 (9 pages) (No. 232 paper)(A-49) H. Fujishiro, Y. Noda, K. Akuzawa, T. Naito, A. Ito, T. Goto, M. Marysko, Z. Jirak, J. Hejtmanek and K.
Nitta, “Electrical resistivity anomaly, valence shift of Pr ion and magnetic behavior in epitaxial(Pr1-yYy)1-xCaxCoO3 thin films under compressive strain”,
J. Appl. Phys. 121 (2017) 115104 (8 pages) (DOI: 10.1063/1.4978747）(No. 246 paper)

B. 酸化物超電導体の熱物性（熱伝導率、熱拡散率、熱起電⼒） 30 編
(B-1) M. Ikebe, H. Fujishiro, T. Naito, K. Noto, S. Kohayashi and S. Yoshizawa, “Thermal conductivity of
YBCO(123) and YBCO(211) mixed crystals prepared by MMTG”,
Cryogenics 34 (1994) pp. 57-61 (No. 14 paper)(B-2) M. Ikebe, H. Fujishiro, T. Naito and K. Noto, “Simultaneous Measurement of Thermal Diffusivity andConductivity Applied to Bi-2223 Ceramic Superconductors”,
J. Phys. Soc. Jpn. 63 (1994) pp. 3107-3114 (No. 16 paper)(B-3) M. Matsukawa, K. Noto, H. Fujishiro, T. Todate, K. Mori, Y. Yamada and M. Ishihara, “THERMAL
TRANSPORT AND SCATTERING MECHANISMS IN BPSCCO HIGH-Tc SUPERCONDUCTORS”,
Physica B 194-196 (1994) pp. 2217-2218 (No. 17 paper)(B-4) M. Matsukawa, F. Tatezaki, K. Noto, H. Fujishiro, K. Michishita and Y. Kubo, “Thermal conductivity of
Ag-doped Bi-2212 superconducting materials prepared by the floating method”,
Cryogenics 34 (1994) pp. 685-688 (No. 23 paper)(B-5) H. Fujishiro, M. Ikebe, T. Naito, K. Noto, S. Kohayashi and S. Yoshizawa, “Anisotropic Thermal Diffusivity
and Conductivity of YBCO(123) and YBCO(211) Mixed Crystals I”,
Jpn. J. Appl. Phys. 33 (1994) pp. 4965-4970 (No. 24 paper)(B-6) H. Fujishiro, M. Ikebe, T. Naito and K. Noto, “Phonon Thermal Diffusivity and Conductivity of Oxygen
Deficient YBa2Cu3O7”,
Physica C 235-240 (1994) pp. 825-826 (No. 26 paper)(B-7) H. Ogasawara, M. Matsukawa, K. Noto, H. Sato, H. Fujishiro, Y. Kashiwaba, S. Fujinuma, K. Mori and Y.
Hidaka, “In-plane thermal conductivity of Ln2-xCexCuO4-y single crystals (Ln = Nd and Pr) with the T'-phasestructure”,
Physica C 235-240 (1994) pp. 1399-1400 (No. 27 paper)(B-8) H. Fujishiro, M. Ikebe, T. Naito, M. Matsukawa, K. Noto, I. Shigaki, K. Shibutani, S. Hayashi and R.
Ogawa, “Thermal Conductivity of Bi-2212 Single Crystals Prepared by TSFZ Method”,
Physica C 235-240(1994) pp. 1533-1534 (No. 28 paper)(B-9) M. Ikebe, H. Fujishiro, T. Naito, M. Matsukawa and K. Noto, “Anisotropic Thermal Diffusivity andConductivity of YBCO(123) and YBCO(211) Mixed Crystals II”,
Jpn. J. Appl. Phys. 33 (1994) pp. 6157-6159 (No. 30 paper)(B-10) H. Fujishiro, M. Ikebe, M. Yagi, M. Matsukawa, H. Ogasawara and K. Noto, “Thermal Conductivity andDiffusivity of Nd2-XCeXCuO4”,
Physica B 219&220 (1996) pp. 163-165 (No. 32 paper)(B-11) H. Fujishiro, M. Ikebe, K. Nakasato and K. Noto, “Influence of Cu site impurities on the thermal
conductivity of YBa2Cu3O7-d”,
Physica C 263 (1996) pp. 305-308 (No. 33 paper)8－6－

(B-12) M. Ikebe, H. Fujishiro, K. Nakasato and K. Noto, “Thermal conductivity of REBa2Cu3O7 (RE = Y, Dy,
Sm, Nd) superconductors”,
Physica C 263 (1996) pp. 309-312 (No. 34 paper)(B-13) H. Fujishiro, K. Nakasato, S. Takahashi and M. Ikebe, “Effect of Y-site and Ba-site Substitution on
Thermal Properties of YBa2Cu3O7-d”,
Czech. J. Phys. 46 (1996) Suppl. S3, pp. 1207-1208 (No. 38 paper)(B-14) M. Ikebe, H. Fujishiro, Y. Obi, H. Fujimori and K. Noto, “Transport and Thermal Properties of Amorphous
Mn-Y Alloys”,
Czech. J. Phys. 46 (1996) Suppl. S4, pp. 2241-2242 (No. 39 paper)(B-15) H. Fujishiro, M. Ikebe, M. Yagi, K. Nakasato, Y. Shibazaki and T. Fukase, “Thermal Conductivity andPhonon Scattering Mechanisms in La2-XMXCuO4”,
J. Low Temp. Phys. 105 (1996) pp. 981-986 (No. 41 paper)(B-16) M. Ikebe, H. Fujishiro, M. Yagi and T. Fukase, “Effect of annealing on thermal and electrical transport in
Nd1.85Ce0.15CuO4”,
Superlattices and Microstructures 21 (1997) pp. 357-362 (No. 44 paper)(B-17) M. Ikebe, H. Fujishiro and K. Nakasato, “Energy Gap Symmetry and Thermal Conductivity of
YBa2Cu3O7”,
J. Low Temp. Phys. 107 (1997) pp. 467-472 (No. 46 paper)(B-18) H. Fujishiro, M. Ikebe, Y. Konno and T. Fukase, “Sound Velocity Anomaly Associated with Polaron
Ordering in La1-XSrXMnO3”,
J. Phys. Soc. Jpn. 66 (1997) pp. 3703-3705 (No. 48 paper)(B-19) M. Ikebe, H. Fujishiro, K. Nakasato, T. Mikami, T. Naito and T. Fukase, “Thermal Transport in 90 K- and
60 K-phase YBa2Cu3O7-d High-Tc Oxides”,
phys. stat. sol. (b) 209 (1998) pp. 413-426 (No. 54 paper)(B-20) M. Ikebe and H. Fujishiro, “Enhanced phonon scattering due to 3d-transition metal substitution for Cu in
YBa2Cu3O7-d”,
Physica B 263-264 (1999) pp. 636-639 (No. 55 paper)(B-21) H. Fujishiro, M. Ikebe and Y. Shibazaki, “Enhanced Phonon Scattering below Tc Caused by Zn and Ni
Substitution in La1.85Sr0.15CuO4”,
J. Low Temp. Phys. 117 (1999) pp. 1181-1185 (No. 59 paper)(B-22) M. Ikebe, H. Fujishiro and K. Noto, “ANISOTROPIC Ag CONTRIBUTION TO TRANSPORTPHENOMENA IN Ag-Bi2Sr2CaCu2Oy BULK CRYSTAL”,
Advances in Science and Technology 23 (1999) pp. 421-428 (No. 60 paper)(B-23) H. Fujishiro, M. Ikebe and Y. Shibazaki, “THERMAL CONDUCTIVITY OF T*-PHASE(Nd1-x-yCexSry)2CuO4 OXIDE SUPERCONDUCTORS”,
Advances in Science and Technology 23 (1999) pp. 429-436 (No. 61 paper)(B-24) H. Fujishiro, M. Ikebe and T. Fukase, “ULTRASONIC AND PHONON THERMAL TRANSPORTSTUDIES ON YBa2Cu3O7-d OXIDE SUPERCONDUCTORS”,
Advances in Science and Technology 23 (1999) pp. 437-444 (No. 62 paper)(B-25) M. Ikebe and H. Fujishiro, “Heat transport in T*-phase (Nd1-x-yCexSry)2CuO4 superconductors”,
Physica B 284-288 (2000) pp. 1007-1008 (No. 68 paper)(B-26) H. Fujishiro, M. Ikebe and T. Takahashi, “Preparation of RuSr2GdCu2O8 Compounds with Enhanced
Superconducting Transition Temperature”,
J. Low Temp. Phys., Vol. 131, (2003) pp. 589-593 (No. 90 paper)(B-27) T. Naito, K. Sato, D. Yamaguchi and H. Fujishiro, “Vortex Pinning Properties of (Y1-XLaX)-Ba-Cu-O and(Y1-XPrX)-Ba-Cu-O Superconducting Bulks”,
Physica C 469 (2009) pp. 1218-1230 (No. 163 paper)
9－7－

(B-28) T. Naito, S. Ohata, T. Konno and H. Fujishiro, “La-site Substitution Effect by Ce Ion on Carrier
Concentration and Structural Phase Transition in La2-xSrxCuO4”,
Physica C 470 (2010) pp. S261-S262 (No. 176 paper)(B-29) T. Naito, D. Yamaguchi and H. Fujishiro, “Anisotropic Thermal Conductivity of RE2CuO4 (RE = Pr, Nd,
and Sm) Single Crystals Grown by TSFZ Method”,
Chinese Journal of Physics (CJP) 49 (2011) pp. 331-334 (No. 177 paper)(B-30) T. Naito, Y. Ueno and H. Fujishiro, “Relationship between structural phase transition and carrier
concentration in La2-x-ySrxRyCuO4 (R = Ce or Tb)”,
Physica C 471 (2011) pp. 690-692 (No. 184 paper)

C. 超伝導線材、シース合⾦材料の熱物性 13 編
(C-1) H. Fujishiro, M. Ikebe, K. Noto, T. Sasaoka, K. Nomura, “Thermal and electrical properties of Ag-Au andAg-Cu Alloy tapes for the metal stabilizer of oxide superconductors”,
Cryogenics 33 (1993) pp. 1086-1090 (No. 13 paper)(C-2) T. Sasaoka, K. Nomura, J. Sato, S. Kuma, H. Fujishiro, M. Ikebe and K. Noto, “Characteristics of Ag-Au
alloy sheathed Bi-Pb-Sr-Ca-Cu-O superconducting tapes for current leads”,
Appl. Phys. Lett. 64 (1994) pp. 1304-1305 (No. 18 paper)(C-3) H. Fujishiro, M. Ikebe, K. Noto, M. Matsukawa, T. Sasaoka, K. Nomura, J. Sato and S. Kuma, “Low
Thermal Conductive Bi-2223 Tapes Sheathed with Ag-Au Alloys”,
IEEE Trans. Mag. 30 (1994) pp. 1645-1650 (No. 21 paper)(C-4) T. Naito, H. Fujishiro, Y. Yamada, “Thermal conductivity and thermal dilatation of Bi2223 sheathed tape”,
IEEE Trans. Appl. Supercond. 19 (2009) pp. 3034-3036 (No. 159 paper)(C-5) T. Naito, H. Fujishiro and Y. Yamada, “Thermal conductivity of single and multi-stacked DI-BSCCO tapes”,
Cryogenics 49 (2009) pp. 429-432 (No. 161 paper)(C-6) T. Naito, H. Fujishiro and Y. Yamada, “Thermal conductivity of DI-BISCCO tapes with stacked or
sandwiched structure”,
J. Phys. Conf. Series 234 (2010) 022025 (No. 169 paper)(C-7) T. Naito, H. Fujishiro and Y. Yamada, “Anisotropic thermal transport in double-pancake coil wound with
DI-BISCCO tape”,
Physica C 470 (2010) pp. 1397-1400 (No. 172 paper)(C-8) T. Naito, H. Fujishiro, H. Okamoto, H. Hayashi, Y. Gosho, N. Fujiwara and Y. Shiohara, “Thermal
conductivity of YBCO coated conductors fabricated by IBAD-PLD method”,
Supercond. Sci. Technol. 23 (2010) 105013 (4 pages) (No. 173 paper)(C-9) T. Naito, H. Fujishiro, H. Okamoto, H. Hayashi, Y. Gosho, N. Fujiwara, Y. Shiohara, “Thermal conductivity
of YBCO coated conductors reinforced by metal tape”,
IEEE Trans. Appl. Supercond. 21 (2011) pp. 3037-3040 (No. 181 paper)(C-10) T. Naito, H. Fujishiro and J. Fujikami, “Anisotropic thermal conductivity of silver sheathed Bi2223
superconducting tape “,IEEE Trans. Appl. Supercond. 21 (2011) pp. 2828-2831 (No. 182 paper)(C-11) T. Naito, H. Fujishiro, Y. Yamamura, K. Saito, H. Okamoto, H. Hayashi, Y. Gosho, T. Ohkuma, and Y.
Shiohara, “Specific heat and thermal diffusivity of YBCO coated conductors”,
Physics Procedia, 36 (2012) pp. 1609-1613 (No. 196 paper)(C-12) T. Naito, H. Fujishiro, G. Osabe and J. Fujigami, “Anisotropic thermal transport in Bi2223/Ag
superconducting tape with sandwiched structure”,
Physica C 484 (2012) pp. 159-162 (No. 199 paper)

10－8－(C-13) Tomoyuki Naito, Hiroyuki Fujishiro, and Yuichi Yamada, “Thermal conductivity and dilatation of a
Bi-2223/Ag (DI-BISCCO) superconducting wire laminated with Ni-alloy tapes”,
IEEE Trans. Appl. Supercond. 28 (2018) 6400404 (DOI: 10.1109/TASC.2018.2796382) (No. 259 paper)

D. 熱物性測定技術の開発（熱拡散率測定、2 次元熱伝導率測定、接触熱抵抗測定） 6 編(D-1) 藤代博之、内藤智之、池部 学、能登宏七、「低温における熱拡散率と熱伝導率の同⼀セッティ
ング測定」、
低温⼯学 28 (1993) pp. 533-539 (No. 10 paper)(D-2) 藤代博之、池部 学、内藤智之、能登宏七、「Bi 系酸化物超伝導体の同⼀セッティングによる熱
拡散率、熱伝導率測定」、
低温⼯学 28 (1993) pp. 582-587 (No. 11 paper)(D-3) 保原夏朗、松川倫明、松浦伸悌、藤代博之、能登宏七、「ヘリウム冷凍機を⽤いた熱伝導率の完
全⾃動測定」、
低温⼯学 28 (1993) pp. 688-692 (No. 12 paper)(D-4) H. Fujishiro, M. Ikebe, K. Nakasato and T. Naito, “Proposal of Three Terminal Method for Low
Temperature Thermal Diffusivity Measurement”,
Czech. J. Phys. 46 (1996) Suppl. S5, pp. 2761-2762 (No. 40 paper)(D-5) H. Fujishiro, T. Okamoto, M. Ikebe and K. Hirose, “A New Method for Simultaneous Determinationof Anisotropic Thermal Conductivities Based on Two-Dimensional Analyses”,
Jpn. J. Appl. Phys. 40 (2001) pp. 388-392 (No. 71 paper)(D-6) H. Fujishiro, T. Okamoto and K. Hirose, “Thermal contact resistance between high-Tc superconductor andcopper”,
Physica C 357-360 (2001) pp. 785-788 (No. 76 paper)

E. REBaCuO 系超電導バルクの熱物性 12 編
(E-1) H. Fujishiro and S. Kohayashi, “Thermal Conductivity, Thermal Diffusivity and Thermoelectric Power of
Sm-Based Bulk Superconductors”,
IEEE Trans. Appl. Supercond. 12 (2002) pp. 1124-1127 (No. 84 paper)(E-2) 藤代博之、池部 学、能登宏七、⼿嶋英⼀、澤村 充、「GdBaCuO 系バルク超伝導体の熱的性質—YBaCuO 系との⽐較—」,
低温⼯学 37 (2002) pp. 659-664 (No. 85 paper)(E-3) ⼿嶋英⼀、平野芳⽣、藤代博之、「0.5 T - 77 K で動作可能な 250A 級 Y 系⾼温超電導バルク電流リード」,
低温⼯学 37 (2002) pp. 718-725 (No. 86 paper)(E-4) H. Fujishiro, M. Ikebe, S. Kohayashi, K. Noto and K. Yokoyama, “Additional effect of Ag and 211 phase on
thermal expansion of REBaCuO bulk superconductor (RE = Sm, Y),
Cryogenics 43 (2003) pp. 477-481 (No. 89 paper)(E-5) H. Fujishiro, H. Teshima, M. Ikebe and K. Noto, “Thermal conductivity of YBaCuO bulk superconductors
under applied field: effect of content and size of Y211 phase”,
Physica C 392-396 (2003) P1, pp. 171-174 (No. 94 paper)(E-6) K. Noto, T. Oka, K. Yokoyama, K. Katagiri, H. Fujishiro, H. Okada, H. Nakazawa, M. Muralidhar and M.
Murakami, “Thermal and mechanical properties of high Tc bulk superconductors and their applications”,
Physica C 392-396 (2003) pp. 677-683 (No. 95 paper)(E-7) H. Fujishiro, K. Katagiri, A. Murakami, Y. Yoshino and K. Noto, “Database for thermal and mechanicalproperties of REBaCuO bulks”,
Physica C 426-431 (2005) pp. 699-704 (No. 121 paper)11－9－

(E-8) H. Fujishiro, S. Nariki and M. Murakami, “Thermal Conductivity and Thermoelectric Power of DyBaCuO
Bulk Superconductor”,
Supercond. Sci. Technol. 19 (2006) pp. S447-S450 (No. 130 paper)(E-9) H. Fujishiro, M. Ikebe, H. Teshima and H. Hirano, “Low-Thermal-Conductive DyBaCuO Bulk
Superconductor for Current Lead Application”,
IEEE Trans. Appl. Supercond. 16 (2006) pp. 1080-1083 (No. 133 paper)(E-10) T. Naito, H. Fujishiro, K. Iida, S. Nariki and M. Murakami, “Thermal Conductivity of Er-Ba-Cu-O and
Ho-Ba-Cu-O superconducting bulks”,
Supercond. Sci. Technol. 21 (2008) 085001 (4 pages) (No. 148 paper)(E-11) T. Naito, H. Fujishiro, K. Iida and M. Murakami, “Anisotropic Thermal Conductivity of Er-Ba-Cu-O Bulk
Superconductors”,
Physica C 468 (2008) pp. 1428-1430 (No. 152 paper)(E-12) T. Naito, D. Furuta, T. Arayashiki, H. Fujishiro, Y. Yanagi and Y. Itoh, “Position dependence ofirreversibility line on thin plate Gd-Ba-Cu-O bulk superconductor”,
Physics Procedia 27 (2012) pp. 168-171 (No. 191 paper)

F. REBaCuO 系超電導バルク磁⽯の開発 59 編
(F-1) H. Fujishiro, T. Oka, K. Yokoyama and K. Noto, “Time evolution and spatial distribution of temperature in
YBCO bulk superconductor after pulse field magnetizing”,
Supercond. Sci. Technol. 16 (2003) pp. 809-814 (No. 97 paper)(F-2) H. Fujishiro, K. Yokoyama, T. Oka and K. Noto, “Temperature rise in an Sm-based bulk superconductor
after applying iterative pulse fields”,
Supercond. Sci. Technol. 17 (2004) pp. 51-57 (No. 103 paper)(F-3) H. Fujishiro, T. Oka, K. Yokoyama, M. Kaneyama and K. Noto, “Flux Motion Studies by Means ofTemperature Measurement in Magnetizing Processes for HTSC Bulks”,
IEEE Trans. Applied Supercond. 14 (2004) pp. 1054-1057 (No. 104 paper)(F-4) H. Fujishiro, K. Yokoyama, M. Kaneyama, T. Oka and K. Noto, “Estimation of generated heat in pulse fieldmagnetizing for SmBaCuO bulk superconductor”,
Physica C 412-414 (2004) pp. 646-650 (No. 105 paper)(F-5) K. Yokoyama, M. Kaneyama, T. Oka, H. Fujishiro and K. Noto, “Temperature measurement of RE123 bulk
superconductors on magnetizing process”,
Physica C 412-414 (2004) pp. 688-694 (No. 106 paper)(F-6) H. Fujishiro, M. Kaneyama, K. Yokoyama, T. Oka and K. Noto, “Generated heat during pulse fieldmagnetizing for REBaCuO (RE = Gd, Sm, Y) bulk superconductors with different pinning ability”,
Supercond. Sci. Technol. 18 (2005) pp. 158-165 (No. 109 paper)(F-7) H. Fujishiro, K. Yokoyama, M. Kaneyama, T. Oka and K. Noto, “Effect of Metal Ring Setting Outside
HTSC Bulk Disk on Trapped Field and Temperature Rise in Pulse Filed Magnetizing”,
IEEE Trans. Appl. Supercond. 15 (2005) pp. 3762-3765 (No. 112 paper)(F-8) H. Fujishiro, M. Kaneyama, K. Yokoyama, T. Oka and K. Noto, “Rise-Time Elongation Effects on Trapped
Field and Temperature Rise in Pulse Field Magnetization for High Temperature Superconducting Bulk”,
Jpn. J. Appl. Phys. 44 (2005) pp. 4919-4925 (No. 115 paper)(F-9) ⾦⼭雅彦、藤代博之、横⼭和哉、岡 徹雄、能登宏七、「20-40 K における Sm-Ba-Cu-O バルクに対するパルス着磁による捕捉磁場と発熱解析」、
低温⼯学 40 (2005) pp. 231-237 (No. 116 paper)(F-10) H. Fujishiro, M. Kaneyama, T. Tateiwa and T. Oka, “Record High Trapped Field by Pulse Field
Magnetization Using GdBaCuO Bulk Superconductor”,
Jpn. J. Appl. Phys. 44 (2005) pp. L1221-L1224 (No. 118 paper)12－ 10 －

(F-11) H. Fujishiro, K. Yokoyama, M. Kaneyama, M. Ikebe, T. Oka and K. Noto, “Approach from temperature
measurement to trapped field enhancement in HTSC bulks by pulse field magnetizing”,
Physica C 426-431 (2005) pp. 594-601 (No. 119 paper)(F-12) K. Yokoyama, M. Kaneyama, H. Fujishiro, T. Oka and K. Noto, “Temperature rise and trapped field in a
GdBaCuO bulk superconductor cooled down to 10 K after applying pulse magnetic field”,
Physica C 426-431 (2005) pp. 671-675 (No. 120 paper)(F-13) T. Oka, K. Yokoyama, H. Fujishiro, M. Kaneyama and K. Noto, “Temperature changes in a melt-processed
YBCO superconductor activated by field cooling magnetizing process”,
Physica C 426-431 (2005) pp. 794-799 (No. 122 paper)(F-14) H. Fujishiro, M. Kaneyama, T. Tateiwa and T. Oka, “Trapped Field over 4 Tesla on GdBaCuO Bulk byPulse Field Method and Magnetizing Mechanism”,
J. Phys.: Conf. Series 43 (2006) pp. 405-408 (No. 126 paper)(F-15) H. Fujishiro, S. Kawaguchi, M. Kaneyama, A. Fujiwara, T. Tateiwa and T. Oka, “Heat Propagation
Analysis in HTSC Bulks during Pulse Field Magnetization”,
Supercond. Sci. Technol. 19 (2006) S540-S544 (No. 131 paper)(F-16) H. Fujishiro, A. Fujiwara, T. Tateiwa, T. Oka and H. Hayashi, “New Type Superconducting Bulk Magnet
by Pulse Field Magnetization with Usable Surface on Both-sides in Open Space”,
IEEE Trans. Appl. Supercond. 16 (2006) 1080-1083 (No. 132 paper)(F-17) Hiroyuki Fujishiro, Tatsuya Tateiwa, Atsushi Fujiwara, Tetsuo Oka and Hidemi Hayashi, “Higher trappedfield over 5 Tesla on HTSC bulk by modified pulse field magnetizing”,
Physica C 445-448 (2006) pp. 334-338 (No. 134 paper)(F-18) A. Fujiwara, T. Tateiwa, H. Fujishiro, H. Hayashi, T. Nagafuchi and T. Oka, “Development of five aligned
superconducting bulk magnets by pulse field magnetizing”,
Physica C 445-448 (2006) pp. 399-402 (No. 135 paper)(F-19) 藤原 篤、⽴岩達也、藤代博之、林 秀美、永渕尚志、岡 徹雄、「パルス着磁による ab ⾯⽅向冷却型超伝導バルク磁⽯の伝熱解析---c 軸⽅向冷却との⽐較 ---」
低温⼯学 41 (2006) pp. 390-396 (No. 136 paper)(F-20) H. Fujishiro, T. Tateiwa, T. Hiyama, Y. Sazuka and T. Oka, “Enhancement of Trapped Field and Total
Trapped Flux on High Temperature Bulk Superconductor by a New Pulse-Field Magnetization Method”,
Jpn. J. Appl. Phys. 46 (2007) pp. 4108-4112 (No. 140 paper)(F-21) H. Fujishiro, T. Tateiwa, K. Kakehata, T. Hiyama and T. Naito, “Trapped Field and Temperature Rise on
f65 mm GdBaCuO Bulk by Pulse Field Magnetization”,
Supercond. Sci. Technol. 20 (2007) pp. 1009-1014 (No. 141 paper)(F-22) H. Fujishiro, T. Hiyama, T. Tateiwa, Y. Yanagi and T. Oka, “Importance of initial M-shaped trapped field
profile using a two-step pulse field magnetization (MMPSC) method”,
Physica C 463-465 (2007) pp. 394-397 (No. 142 paper)(F-23) T. Tateiwa, Y. Sazuka, H. Fujishiro, H. Hayashi, T. Nagafuchi and T. Oka, “Trapped field and temperaturerise in rectangular shaped HTSC bulk magnetized by pulse fields”,
Physica C 463-465 (2007) pp. 398-401 (No. 143 paper)(F-24) K. Yokoyama, T. Oka, H. Fujishiro, “Evaluation of Current Distribution of Bulk Superconductors
Magnetized by Pulsed Field”
Physica C 463-465 (2007) pp. 410-414 (No. 144 paper)(F-25) T. Oka, K. Yokoyama, H. Fujishiro and K. Noto, “Temperature Rise in Melt-Textured Large Grain
Superconducting Bulk Magnets during Magnetizing Processes”,
Physica C 460-462 (2007) pp. 748-749 (No. 145 paper)(F-26) K. Yokoyama, T. Oka, H. Fujishiro and K. Noto, “Numerical Analysis of Bulk Superconducting Magnet
Magnetized by Pulsed-Field Considering a Partial Difference of Superconducting Characteristics”,
IEEE Trans. Appl. Supercond. 18 (2008) pp. 1545-1548 (No. 146 paper)13－ 11 －

(F-27) K. Kajikawa, R. Yokoo, K. Tomachi, K. Enpuku, K. Funaki, H. Hayashi and H. Fujishiro, “Numerical
Evaluation of Pulsed Field Magnetization in a Bulk Superconductor Using Energy Minimization Technique”,
IEEE Trans. Appl. Supercond. 18 (2008) pp. 1557-1560 (No. 147 paper)(F-28) T. Hiyama, H. Fujishiro, T. Tateiwa, T. Naito, H. Hayashi and K. Tone, “Trapped Field Enhancement ofFive-aligned Superconducting Bulk Magnetized by Pulse Field for Magnetic Separation”
Physica C 468 (2008) pp. 1469-1472 (No. 150 paper)(F-29) H. Fujishiro, T. Tateiwa, K. Kakehata, T. Hiyama, T. Naito and Y. Yanagi, “Trapped field characteristics on
f65 mm GdBaCuO bulk by modified multi-pulse technique with stepwise cooling (MMPSC)”,
Physica C 468 (2008) pp. 1477-1480 (No. 151 paper)(F-30) K. Kajikawa, R. Yokoo, K. Tomachi, K. Enpuku, K. Funaki, H. Hayashi and H. Fujishiro, “Finite element
analysis of pulse field magnetization process in a cylindrical bulk superconductor”,
Physica C 468 (2008) pp. 1494-1497 (No. 153 paper)(F-31) H. Fujishiro, T. Hiyama, T. Naito, T. Tateiwa and Y. Yanagi, “Possible explanation for trapped fieldenhancement on REBaCuO bulk by modified multi-pulse technique with stepwise cooling (MMPSC)”,
Materials Science and Engineering B, 151 (2008) pp. 95-100 (No. 154 paper)(F-32) T. Oka, K. Yokoyama, H. Fujishiro and K. Noto, “Thermal Behavior and Field-Trapping Property of MeltTextured Superconducting Bulk Magnets Activated by Quasi-Static Magnetic Fields”
J. Phys. Conf. Series 150 (2009) 052195 (4 pages) (No. 156 paper)(F-33) T. Oka, K. Yokoyama, H. Fujishiro and K. Noto, “Thermal and Magnetic Behaviors of Melt-Textured
Superconducting Bulk Magnet in Zero-Field Cooling Magnetizing Process”,
Supercond. Sci. Technol. 22 (2009) 065014 (8 pages) (No. 157 paper)(F-34) H. Fujishiro, T. Hiyama, T. Miura, T. Naito, S. Nariki, N. Sakai, I. Hirabayashi, “Pulsed Field
Magnetization for GdBaCuO Bulk with Stronger Pinning Characteristics”,
IEEE Trans. Appl. Supercond. 19 (2009) pp. 3545-3548 (No. 158 paper)(F-35) H. Fujishiro, T. Hiyama, T. Naito, Y. Yanagi and Y. Itoh, “Enhancement of trapped field and total trapped
flux on GdBaCuO bulk by MMPSC-IMRA method”,
Supercond. Sci. Technol. 22 (2009) 095006 (6 pages) (No. 160 paper)(F-36) H. Fujishiro, K. Kakehata, T. Naito, Y. Yanagi and Y. Itoh, “Enhancement of total trapped fluxes on f65
mm GdBaCuO bulk by multi-pulse techniques”,
Physica C 469 (2009) pp. 1250-1253 (No. 162 paper)(F-37) 岡 徹雄，横⼭和哉，藤代博之，能登宏七、「準静的磁場による磁化過程における溶融超伝導バ
ルク磁⽯の温度変化と磁場特性」、
低温⼯学 44 (2009) pp. 587-593 (No. 164 paper)(F-38) H. Fujishiro, T. Naito, K. Kakehata, Y. Yanagi and Y. Itoh, “Estimation of temperature rise from trappedfield gradient on superconducting bulk magnetized by multi-pulse technique”,
Supercond. Sci. Technol. 23 (2010) 025013 (6 pages) (No. 165 paper)(F-39) H. Fujishiro, T. Naito, T. Miura and H. Hayashi, “Highly efficient magnetic separation using five-aligned
superconducting bulk magnet”,
J. Phys. Conf. Series 234 (2010) 032015 (6 pages) (No. 168 paper)(F-40) H. Fujishiro, K. Kakehata, D. Furuta and T. Naito, “Temperature measurements in small holes drilled in
HTSC bulk during pulsed field magnetization”,
Physica C 470 (2010) pp. 1181-1184 (No. 170 paper)(F-41) H. Fujishiro, D. Furuta, T. Naito, K. Yaegashi and N. Yoshimoto, “Large and spatial magnetic field
modulation using superconducting bulk magnet and silicon steel”,
Physica C 470 (2010) pp. 1856-1859 (No. 171 paper)(F-42) H. Fujishiro, T. Naito, D. Furuta, T. Arayashiki, Y. Yanagi and Y. Itoh, “Direct Jc measurements and trappedfield profiles using an identical superconducting bulk”,
Supercond. Sci. Technol. 24 (2011) 105003 (6 pages) (No. 183 paper)14－ 12 －

(F-43) H. Fujishiro, T. Handa, T. Naito, N. Kikuchi, “Jc distribution measurement and analysis on superconducting
bulk using “Magnetoscan” method”,
Physica C 471 (2011) pp. 893-896 (No. 185 paper)(F-44) T. Oka, H. Seki, T. Kimura, D. Mimura, S. Fukui, J. Ogawa, T. Sato, M. Ooizumi, H. Fujishiro, H.
Hayashi, K. Yokoyama and C. Stiehler, “Magnetic Separation Technique for Ground Water by Five HTS
Melt-Processed Bulk Magnets Arranged in a Line”,
Physica C 471 (2011) pp. 1506-1560 (No. 187 paper)(F-45) H. Fujishiro, T. Arayashiki, T. Tamura, T. Naito, H. Teshima and M. Morita, “Trapped field profiles onsquare-shaped GdBaCuO bulks with different arrangement of growth sector boundaries”,
Jpn. J. Appl. Phys. 51 (2012) 093005 (5 pages) (No. 192 paper)(F-46) Hidekazu Teshima, Mitsuru Morita, Takahiro Arayashiki , Tomoyuki Naito and Hiroyuki Fujishiro, “10 T
Class Trapped Field Properties of a Large Gd-Ba-Cu-O Bulk Superconductor”,
Physics Procedia 45 (2013) pp. 61-64 (No. 206 paper)(F-47) H. Mochizuki, H. Fujishiro, T. Naito, Y. Itoh, Y. Yanagi, and T. Nakamura, “Trapped Field Characteristics
and Fracture Behavior of REBaCuO Bulk Ring During Pulsed Field Magnetization”,
IEEE Trans. Appl. Supercond. 26 (2016) 6800205 (No. 231 paper)(F-48) K Takahashi, H Fujishiro, M. D. Ainslie and T Naito, “Pulsed field magnetizing characteristics ofrectangular-shaped GdBaCuO bulk using split- and solenoid-type coils”,
IEEE Trans. Appl. Supercond. 27 (2017) 6800205 (6 pages) (DOI: 10.1109/TASC.2016.2625764) (No. 241
paper)(F-49) T. Naito, H. Mochizuki, H. Fujishiro and H. Teshima, “Trapped magnetic-field properties of prototype for
Gd-Ba-Cu-O/MgB2 hybrid-type superconducting bulk magnet”,
Supercond. Sci. Technol. 29 (2016) 034005 (8 pages) (DOI: 10.1088/0953-2048/29/3/034005) (No. 242
paper)(F-50) K. Takahashi, M. D. Ainslie, H. Fujishiro, T. Naito, Y-H. Shi, and D. A. Cardwell, “Trapped field propertiesof a Y-Ba-Cu-O bulk using pulsed field magnetization with a split coil with iron yokes of various geometries
and magnetic properties”,
Physica C, 536 (2017) pp. 1-10 (DOI: 10.1016/j.physc.2017.03.005) (No. 247 paper)(F-51) K. Takahashi, H. Fujishiro, T. Naito, Y. Yanagi, Y. Itoh and T. Nakamura, “Fracture behavior by magnetic
stress in EuBaCuO superconducting ring bulk reinforced by a stainless steel during field-cooledmagnetization”,
Supercond. Sci. Technol. 30 (2017) 115006 (9 pages) (No. 250 paper)(F-52) K. Takahashi, S. Namba, H. Fujishiro, T. Naito, Y. Yanagi, Y. Itoh, T. Nakamura; “Thermal and magnetic
strain measurements on REBaCuO ring bulk reinforced by metal ring during field-cooled magnetization”,
Supercond. Sci. Technol. 32 (2019) 015007 (9 pages) (DOI: 10.1088/1361-6668/aaee01) (No. 261paper)(F-53) Tatsuya Hirano, Keita Takahashi, Fumiya Shimoyashiki, Hiroyuki Fujishiro, Tomoyuki Naito, and Mark D.
Ainslie, “Influence of Jc(B, T) Characteristics on the Pulsed Field Magnetization of REBaCuO Disk Bulks”,
IEEE Trans. Appl. Supercond. 29 (2019) 8000705 (5 pages) (DOI: 10.1109/TASC.2018.2872819) (No. 263
paper)(F-54) T. Hirano, H. Fujishiro, T. Naito, M. D. Ainslie and Y-H. Shi, “Flux dynamics and thermal behavior of a
Gd-Ba-Cu-O bulk magnetized by single- and multi-pulse techniques using split-type coil”,
IEEE Trans. Appl. Supercond. 29 (2019) 6801705 (5 pages) (DOI: 10.1109/TASC.2019.2900979) (No. 266
paper)(F-55) F. Shimoyashiki, H. Fujishiro, T. Naito, and M. D. Ainslie, “Trapped field properties of GdBaCuO
superconducting bulk with various diameters magnetized by pulsed field using identical split coil”,
IEEE Trans. Appl. Supercond. 29 (2019) 6802405 (5 pages) (DOI: 10.1109/TASC.2019.2901349) (No. 269
paper)
15－ 13 －

(F-56) Sora Namba, Hiroyuki Fujishiro, Tomoyuki Naito, Mark D Ainslie and Kai Y Huang, “Electromagnetic
strain measurements and bidirectional mechanical stress estimation for a REBaCuO ring bulk reinforced by ametal ring during field-cooled magnetization”
Supercond. Sci. Technol. 32 (2019) 125011 (10 pages) (DOI: 10.1088/1361-6668/ab4a8b) (No. 270 paper)(F-57) T. Naito, H. Fujishiro and S. Awaji, “Field-cooled magnetization of Y-Ba-Cu-O superconducting bulk pair
reinforced by full metal encapsulation under high magnetic fields up to 22 T”,
J. Appl. Phys. 126 (2019) 243901 (8 pages) (DOI: 10.1063/1.5124010) (No. 272 paper)(F-58) D. K. Namburi, K. Takahashi, T. Hirano, T. Kamada, H. Fujishiro, Y-H. Shi, D. A. Cardwell, J. H. Durrell
and M. D. Ainslie, “Pulsed-field magnetisation of Y-Ba-Cu-O bulk superconductors fabricated by the
infiltration growth technique”,
Supercond. Sci. Technol. 33 (2020) 115012 (12 pages) (DOI: 10.1088/1361-6668/abb590) (No. 282 paper)(F-59) Motoki Shinden, D. K. Namburi, Keita Takahashi, Hiroyuki Fujishiro, and Mark D. Ainslie, “Pulsed Field
Magnetization of GdBaCuO Superconducting Bulks with High Magnetization Efficiency Using a Split-Type
Coil with Soft Iron Yoke”,
to be published in IEEE Trans. Appl. Supercond. (2022) (No. 287 paper)

G. 超電導バルク磁⽯の着磁シミュレーション 32 編
(G-1) H. Fujishiro and T. Naito, “Simulation of temperature and magnetic field distribution in superconducting
bulk during pulsed field magnetization”,
Supercond. Sci. Technol. 23 (2010) 105021 (8 pages) (No. 174 paper)(G-2) H. Fujishiro, T. Naito and M. Oyama, “Mechanism of magnetic flux trapping on superconducting bulk
magnetized by pulsed field using a vortex-type coil”,
Supercond. Sci. Technol. 24 (2011) 075015 (7 pages) (No. 179 paper)(G-3) H. Fujishiro, T. Naito and D. Furuta, “Analysis of temperature and magnetic field distribution insuperconducting bulk during pulsed field magnetization”,
IEEE Trans. Appl. Supercond. 21 (2011) pp. 2723-2726 (No. 180 paper)(G-4) H. Fujishiro, T. Naito, M. Oyama, “Simulation of flux dynamics in a superconducting bulk magnetized bymulti-pulse technique”,
Physica C 471 (2011) pp. 889-892 (No. 186 paper)(G-5) H. Fujishiro, T. Naito and M. Oyama, “Size effect of magnetizing solenoid coil for pulsed fieldmagnetization on the trapped field on superconducting bulk”,
IEEE Trans. Appl. Supercond. 22 (2012) 4700204 (4 pages) (No. 193 paper)(G-6) H. Fujishiro, T. Naito and M. Oyama, “Three-dimensional simulation of magnetic flux dynamics andtemperature rise in HTSC bulk during pulsed field magnetization”,
Physics Procedia 36 (2012) pp. 687-692 (No. 195 paper)(G-7) H. Fujishiro, T. Naito, M. Oyama, T. Arayashiki, T. Tamura, T. Sasaki and G. Giunchi, “Numericalsimulation of trapped field and temperature rise in MgB2 bulks magnetized by pulsed field”,
IEEE Trans. Appl. Supercond. 23 (2013) 6800804 (4 pages) (No. 205 paper)(G-8) M. D. Ainslie, H. Fujishiro, T. Ujiie, J. Zou, A. Dennis, Y.-H. Shi and D. A. Cardwell, “Modeling andcomparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed fieldmagnetization”,
Supercond. Sci. Technol. 27 (2014) 065008 (9 pages) (No. 211 paper)(G-9) H. Fujishiro, T. Naito and T. Yoshida, “Numerical simulation of trapped field on MgB2 bulk diskmagnetized by field cooling”,
Supercond. Sci. Technol. 27 (2014) 065019 (7 pages) (No. 212 paper)(G-10) M. D. Ainslie, H. Fujishiro, “Modelling of bulk superconductor magnetization”,
Supercond. Sci. Technol. 28 (2015) 053002 (20 pages) (Topical Review Paper) (No. 219 paper)16－ 14 －

(G-11) J. Zou, M. D. Ainslie, H. Fujishiro, A. G. Bhagurkar, T. Naito, N. Hari Babu, J-F. Fagnard, P.
Vanderbemden, A. Yamamoto, “Numerical modeling and comparison of MgB2 bulks fabricated by HIP and
infiltration growth magnetized by field cooling”,
Supercond. Sci. Technol. 28 (2015) 075009 (9 pages) (No. 223 paper)(G-12) H. Fujishiro, Y. Itoh, Y. Yanagi and T. Nakamura, “Drastic improvement of the trapped field homogeneity
in a superconducting hollow bulk by the insertion of a high-Jc superconducting cylinder for NMR bulk
magnets”,
Supercond. Sci. Technol. 28 (2015) 095018 (8 pages) (No. 226 paper)(G-13) M. D. Ainslie, J. Zou, H. Mochizuki, H. Fujishiro, Y-H. Shi, A. R. Dennis and D. A. Cardwell, “Pulsed
field magnetization of 0°-0° and 45°-45° bridge-seeded Y-Ba-Cu-O bulk superconductors”
Supercond. Sci. Technol. 28 (2015) 125002 (14 pages) (No. 228 paper)(G-14) Mark Douglas Ainslie, Hidehiko Mochizuki, Hiroyuki Fujishiro, Wei Zhai, Yun-hua Shi, Anthony Dennis,
David Anthony Cardwell, “Pulsed field magnetization of single grain YBCO processed from gradedprecursor powders”,
IEEE Trans. Appl. Supercond. 26 (2016) 6800104 (4 pages) (No. 231-2 paper)(G-15) M D Ainslie, H Fujishiro, H Mochizuki, K Takahashi, Y-H Shi, D K Namburi, J Zou, D Zhou, A R Dennis
and D A Cardwell, “Enhanced trapped field performance of bulk high-temperature superconductors using
split coil, pulsed field magnetization with an iron yoke”
Supercond. Sci. Technol. 29 (2016) 074003 (16 pages) (No. 233 paper)(G-16) M. D. Ainslie, D. Zhou, H. Fujishiro, K. Takahashi, Y-H. Shi and J. H. Durrell, “Flux jump-assisted pulsed
field magnetization of high-Jc bulk high-temperature superconductors”,
Supercond. Sci. Technol. 29 (2016) 124004 (9 pages) (No. 238 paper)(G-17) 藤代博之、柳 陽介、伊藤佳孝、仲村⾼志、「超電導各層円筒内挿による NMR ⽤超電導バルクの捕捉磁場均⼀化のシミュレーション解析 —円筒の位置、⻑さ、形状の影響—」、
低温⼯学 52 (2017) pp. 33-37 (DOI: 10.2221/jcsj.52.33) (No. 244 paper)(G-18) M. D. Ainslie, H. Fujishiro, K. Takahashi, Y-H. Shi, D. A. Cardwell, “Pulsed field magnetization of bridgeseeded, bulk YBCO using solenoid and split coils”,
IEEE Trans. Appl. Supercond. 27 (2017) 6801105 (5 pages) (DOI: 10.1109/TASC.2017.2667621) (No. 245
paper)(G-19) H. Fujishiro, M. D. Ainslie, K. Takahashi, T. Naito, Y. Yanagi, Y. Itoh and T. Nakamura, “Simulation
studies of mechanical stresses in REBaCuO superconducting ring bulks with infinite and finite heightreinforced by metal ring during field-cooled magnetization”,
Supercond. Sci. Technol. 30, 085008 (2017) (12 pages) (DOI: 10.1088/1361-6668/aa76a2) (No. 249 paper)(G-20) Mark D. Ainslie, Akiyasu Yamamoto, Hiroyuki Fujishiro, Jeremy D. Weiss and Eric E. Hellstrom,“Numerical modelling of iron-pnictide bulk superconductor magnetization”,
Supercond. Sci. Technol. 30 (2017) 105009 (7 pages) (No. 251 paper)(G-21) Mark D Ainslie, Jan Srpcic, Hiroyuki Fujishiro, Difan Zhou, Keita Takahashi, Fernando Perez, David A
Cardwell, John H Durrell, “Towards optimization of multi-pulse, multi-temperature pulsed fieldmagnetization of bulk high-temperature superconductors”,
IEEE Trans. Appl. Supercond. 28 (2018) 6800207 (7 pages) (DOI: 10.1109/TASC.2017.2788924) (No. 255
paper)(G-22) K. Takahashi, H. Fujishiro, T. Naito, Y. Yanagi, Y. Itoh and T. Nakamura, “Numerical simulation ofelectromagnetic and thermal hoop stresses in REBaCuO superconducting ring and disk bulks reinforced bystainless steel ring with various thicknesses during field-cooled magnetization”,
IEEE Trans. Appl. Supercond. 28 (2018) 6800705 (5 pages) (DOI: 10.1109/TASC.2018.2799578) (No. 256
paper)

17－ 15 －

(G-23) H. Fujishiro, K. Takahashi, T. Naito, Y. Yanagi, Y. Itoh and T. Nakamura, “A new proposal of mechanicalreinforcement structures to annular REBaCuO bulk magnet for compact and cryogen-free NMR
spectrometer”,
Physica C 550 (2018) pp. 52-56 (DOI: 10.1016/j.physc.2018.04.012) (No. 258 paper)(G-24) M. D. Ainslie, K. Y. Huang, H. Fujishiro, J. Chaddock, K. Takahashi, S. Namba, D. A. Cardwell and J. H.
Durrell, “Numerical modelling of mechanical stresses in bulk superconductor magnets with and without
mechanical reinforcement”
Supercond. Sci. Technol. 32 (2019) 034002 (17 pages) (DOI: 10.1088/1361-6668/aaf851) (No. 262 paper)(G-25) H. Fujishiro, T. Naito and S. Awaji, “Proposal of effective mechanical reinforcement structure for
REBaCuO disk bulk pair by full metal encapsulation to achieve higher trapped field over 20 T”,
Supercond. Sci. Technol. 32 (2019) 045005 (9 pages) (DOI: 10.1088/1361-6668/ab0017) (No. 264 paper)(G-26) H. Fujishiro, K. Takahashi, T. Naito, Y. Itoh, Y. Yanagi, T. Nakamura and M. D. Ainslie, “Influence ofInner Diameter and Height of Ring-shaped REBaCuO Bulks on Electromagnetic and Mechanical Properties
during Field-cooled Magnetization”,
IEEE Trans. Appl. Supercond. (2019) 29 6801206 (6 pages) (DOI: 10.1109/TASC.2019.2896782) (No. 267
paper)(G-27) H. Fujishiro, T. Naito, Y. Yanagi, Y. Itoh and T. Nakamura, “Promising effects of a new hat structure anddouble metal ring for mechanical reinforcement of REBaCuO ring-shaped bulk during field-cooledmagnetization at 10 T without fracture”,
Supercond. Sci. Technol. 32 (2019) 065001 (12 pages) (DOI: 10.1088/1361-6668/ab0bed) (No. 268 paper)(G-28) T. Hirano, H. Fujishiro, T. Naito and M. D Ainslie, “Numerical simulation of flux jump behavior in
REBaCuO ring bulks with an inhomogeneous Jc profile during pulsed field magnetization”,
Supercond. Sci. Technol. 33 (2020) 044003 (11 pages) (DOI: 10.1088/1361-6668/ab7297) (No. 273 paper)(G-29) F. Shimoyashiki, H. Fujishiro, T. Hirano, T. Naito and M. D. Ainslie, "Simulation of mechanical stress in
REBaCuO disk bulk magnetized by pulsed-field",
J. Phys. Conf. Series 1559 (2020) 012029 (7 pages) (DOI: 10.1088/1742-6596/1559/1/012029) (No. 277
paper)(G-30) T. Hirano, H. Fujishiro, T. Naito and M. Ainslie, “Simulation of mechanical stresses in reinforced
REBaCuO ring bulks during pulsed-field magnetization”,
J. Phys. Conf. Series 1559 (2020) 012027 (9 pages) (DOI: 10.1088/1742-6596/1559/1/012027) (No. 279
paper)(G-31) V. Cientanni, M. D. Ainslie, H. Fujishiro, K. Takahashi, “Modelling higher trapped fields by pulsed fieldmagnetisation of composite bulk MgB2 superconducting rings”,
Supercond. Sci. Technol. 34 (2021) 114003 (13 pages) (DOI: 10.1088/1361-6668/ac2621) (No. 286 paper)(G-32) Motoki Shinden, Hiroyuki Fujishiro, Keita Takahashi and Mark D Ainslie, “Possibility of mechanicalfracture of superconducting ring bulks due to thermal stress induced by local heat generation during pulsedfield magnetization”,
to be published in Supercond. Sci. Technol. (2022) (No. 288 paper)

H. ハイブリッド型超電導バルク磁⽯の開発 10 編
(H-1) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A new concept of hybrid trapped field magnet lens
(HTFML)”,
Supercond. Sci. Technol. 31 (2018) 044005 (9 pages) (DOI: 10.1088/1361-6668/aaae94) (No. 257 paper)(H-2) S. Namba, H. Fujishiro, M. D. Ainslie, K. Takahashi, T. Naito, Devendra K. Namburi, and Difan Zhou,“Design optimization of a hybrid trapped field magnet lens (HTFML)”IEEE Trans. Appl. Supercond. 29 (2019) 6801605 (5 pages) (DOI: 10.1109/TASC.2019.2899255) (No. 265
paper)
18－ 16 －

(H-3) Sora Namba, Hiroyuki Fujishiro, Tomoyuki Naito, Mark D Ainslie, Keita Takahashi, “Experimental
realization of a Hybrid Trapped Field Magnet Lens (HTFML) using a GdBaCuO magnetic lens and MgB2
bulk cylinder”,
Supercond. Sci. Technol. Letter 32 (2019) 12LT03 (7 pages) (DOI: 10.1088/1361-6668/ab5048) (No. 271
paper)(H-4) K. Takahashi, H. Fujishiro and M. D. Ainslie, " Simulation study for magnetic levitation in pure water
exploiting the ultra-high magnetic field gradient product of a Hybrid Trapped Field Magnet Lens (HTFML)",
J. Appl. Phys. 127 (2020) 185106 (DOI: 10.1063/5.0005356) (11 pages) (No. 274 paper)(H-5) Sora Namba, Hiroyuki Fujishiro, Tatsuya Hirano, Tomoyuki Naito and Mark D Ainslie, "Optimized
performance of an all-REBaCuO hybrid trapped field magnet lens (HTFML)",
Physica C 575 (2020) 1353690 (8 pages) (DOI: 10.1016/j.physc.2020.1353690) (No. 275 paper)(H-6) S. Namba, H. Fujishiro, T. Naito, M. D. Ainslie and D. Zhou, “Realisation of Hybrid Trapped Field
Magnetic Lens (HTFML) consisting of REBCO bulk lens and REBCO bulk cylinder at 77 K”,
J. Phys. Conf. Series 1559 (2020) 012079 (9 pages) (DOI: 10.1088/1742-6596/1559/1/012079) (No. 278
paper)(H-7) Motoki Shinden, Sora Namba, Tatsuya Hirano, Hiroyuki Fujishiro, Tomoyuki Naito, and Mark D. Ainslie,"Numerical Simulation of a Hybrid Trapped Field Magnet Lens (HTFML) Magnetized by Pulsed Fields",
J. Phys. Conf. Series 1590 (2020) 012048 (8 pages) (DOI: 10.1088/1742-6596/1590/1/012048) (No. 280
paper)(H-8) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A conceptual study of a high gradient trapped field magnet(HG-TFM) providing toward a quasi-zero gravity space on Earth”,
Supercond. Sci. Technol. 34 (2021) 035001 (13 pages) (DOI: 10.1088/1361-6668/abd386) (No. 283 paper)(H-9) K. Takahashi, H. Fujishiro, S. Namba and M. D. Ainslie, “Experimental realization of an all-(RE)BaCuO
hybrid trapped field magnet lens generating a 9.8 T concentrated magnetic field from a 7 T external field”,
Supercond. Sci. Technol. 34 (2021) 05LT02 (9 pages) (DOI: 10.1088/1361-6668/abeb01) (No. 284 paper)(H-10) K. Takahashi, H. Fujishiro and M. D. Ainslie, “Validation of a quasi-microgravity space exploiting a highgradient trapped field magnet (HG-TFM) as a desktop-type magnetic field source”,
to be published in Supercond. Sci. Technol. (2022) (No. 290 paper)

I. MgB2 超電導バルク磁⽯の開発 29 編
(I-1) T. Naito, T. Sasaki and H. Fujishiro, “Trapped magnetic field and vortex pinning properties of MgB2
superconducting bulk fabricated by a capsule method”,
Supercond. Sci. Technol. 25 (2012) 095012 (6 pages) (No. 190 paper)(I-2) T. Naito, T. Sasaki and H. Fujishiro, “A proposal of new fabricating technique of large MgB2 bulk by acapsule method”,
IEEE Trans. Appl. Supercond. 22 (2012) 4401703 (4 pages) (No. 194 paper)(I-3) H. Fujishiro, T. Tamura, T. Arayashiki, M. Oyama, T. Sasaki, T. Naito, G. Giunchi and A. Albisetti, “Pulsed
field magnetization of large MgB2 bulk fabricated by reactive liquid Mg infiltration”
Jpn. J. Appl. Phys. 51 (2012) 103005 (5 pages) (No. 197 paper)(I-4) H. Fujishiro, T. Naito, T. Sasaki, T. Arayashiki, “Trapped field and temperature rise in MgB2 bulks
magnetized by pulsed field”,
Proc. ICEC24-ICMC2012 (2013) pp. 571-574 (No. 200 paper)(I-5) T. Sasaki, T. Naito and H. Fujishiro, “Trapped field and critical density of MgB2 bulk fabricated by a capsulemethod “,Proc. ICEC24-ICMC2012 (2013) pp. 575-578 (No. 201 paper)19－ 17 －

(I-6) T. Sasaki, T. Naito and H. Fujishiro, “Trapped magnetic field of dense MgB2 bulks fabricated under highpressure”,
Physics Procedia 45 (2013) pp. 93-96 (No. 207 paper)(I-7) H. Fujishiro, T Ujiie, T Naito, A Figini Albisetti and G Giunchi, “Trapped magnetic field between double
stacked MgB2 bulks magnetized by pulsed field”,
J. Phys. Conf. Series 507 (2014) 032016 (4 pages) (No. 214 paper)(I-8) T. Ujiie, T. Naito, H. Fujishiro, A. Figini Albisetti and G. Giunchi, “Shielding and trapped field properties oflarge MgB2 bulk”,
Physics Procedia 58 (2014) pp. 306-309 (No. 215 paper)(I-9) H. Fujishiro, T. Naito, T. Ujiie, A. Figini Albisetti and G. Giunchi, “Trapped field and flux dynamics in
MgB2 superconducting bulks magnetized by pulsed field”,
Physics Procedia 58 (2014) pp. 286-289 (No. 216 paper)(I-10) A. Murakami, H. Teshima, T. Naito, H. Fujishiro, T. Kudo, “Mechanical properties of MgB2 bulks”,
Physics Procedia 58 (2014) pp. 98-101 (No. 217 paper)(I-11) T. Yoshida, T. Naito and H. Fujishiro, “Effects of sintering condition on the trapped magnetic field
properties for MgB2 bulks fabricated by in-situ capsule method”,
Physics Procedia 58 (2014) pp. 106-109 (No. 218 paper)(I-12) H. Fujishiro, T. Naito, T. Ujiie, T. Mochizuki, T. Yoshida, “Recent progress of MgB2 bulk magnet
magnetized by pulsed field”,
IEEE Trans. Appl. Supercond. 25 (2015) 6800104 (4 pages) (No. 221 paper)(I-13) T. Yoshida, T. Naito and H. Fujishiro, “Development of 4 T class MgB2 bulk magnets doped by Ti”,
IEEE Trans. Appl. Supercond. 25 (2015) 6801204 (4 pages) (No. 222 paper)(I-14) T. Naito, T. Yoshida and H. Fujishiro, “Ti-doping effects on magnetic properties of dense MgB2 bulk
superconductors”,
Supercond. Sci. Technol. 28 (2015) 095008 (8 pages) (No. 224 paper)(I-15) T. Naito, T. Yoshida and H. Fujishiro, “Trapped magnetic field properties of MgB2 bulks doped with Ti”,
Physics Procedia 67 (2015) pp. 958-962 (No. 225 paper)(I-16) H. Mochizuki, H. Fujishiro, T. Naito, A Figini Albisetti and G. Giunchi, “Trapped field properties ofconcentric circle MgB2 bulk composite magnetized by pulsed field and field cooling”
Supercond. Sci. Technol. 28 (2015) 105004 (7 pages) (No. 227 paper)(I-17) T. Naito, T. Yoshida, H. Mochizuki, H. Fujishiro, R. Basu and A. Szpunar, “Vortex Pinning Properties ofDense Ti-doped MgB2 Bulks Sintered at Different Temperature”,
IEEE Trans. Appl. Supercond. 26 (2016) 6800805 (5 pages) (No. 229 paper)(I-18) H. Fujishiro, H. Mochizuki, M. D. Ainslie and T. Naito, “Trapped field of 1.1 Tesla without flux jumps on
high-Jc MgB2 bulk during pulsed field magnetization using split coil with soft iron yoke”,
Supercond. Sci. Technol. 29 (2016) 084001 (10 pages) (No. 234 paper)(I-19) T. Naito, A. Ogino and H. Fujishiro, “Potential ability of 3 T-class trapped field on MgB2 bulk surface
synthesized by the infiltration-capsule method”,
Supercond. Sci. Technol. 29 (2016) 115003 (6 pages) (No. 235 paper)(I-20) H. Fujishiro, H. Mochizuki, T. Naito, M. D. Ainslie and G. Giunchi, “Flux jumps in high-Jc MgB2 bulks
during pulsed field magnetization”,
Supercond. Sci. Technol. 29 (2016) 034006 (7 pages) (No. 237 paper)(I-21) H. Fujishiro, K. Takahashi, M.D. Ainslie, H. Mochizuki and T. Naito, “Suppression of flux jumps andenhancement of trapped field on high-Jc MgB2 bulk using split-type coil with soft iron yoke during pulsed
field magnetization”,
IEEE Trans. Appl. Supercond. 27 (2017) 6800404 (4 pages) (DOI: 10.1109/TASC.2016.2637363) (No. 239
paper)
20－ 18 －

(I-22) A. Ogino, T. Naito, and H. Fujishiro, “Optimization of infiltration and reaction process for the fabrication ofstrong MgB2 bulk magnets”,
IEEE Trans. Appl. Supercond. 27 (2017) 6800905 (5 pages) (DOI: 10.1109/TASC.2016.2643500) (No. 240
paper)(I-23) T. Naito, Y. Endo and H. Fujishiro, “Enhancement of vortex pinning properties on ex-situ MgB2 bulks usingball-milling and spark plasma sintering processes: the dimensional change in grain boundary pinning”,
Supercond. Sci. Technol. 30 (2017) 095007 (8 pages) (No. 248 paper)(I-24) Y. Takahashi, T. Naito, and H. Fujishiro, “Vortex pinning properties and microstructure of MgB2 heavily
doped with titanium group elements”,
Supercond. Sci. Technol. 30 (2017) 125006 (6 pages) (DOI: 10.1088/1361-6668/aa91ed) (No. 253 paper)(I-25) Tatsuya Hirano, Yuhei Takahashi, Sora Namba, Tomoyuki Naito and Hiroyuki Fujishiro, “A record-hightrapped field of 1.61 T in MgB2 bulk comprised of copper plates and soft iron yoke cylinder using pulsedfield magnetization”,
Supercond. Sci. Technol. 33 (2020) 085002 (10 pages) (DOI: 10.1088/1361-6668/ab9542) (No. 276 paper)(I-26) Tomoyuki Naito, Arata Ogino, Hiroyuki Fujishiro, Satoshi Awaji, “Effects of Carbon Doping on Trapped
Magnetic Field of MgB2 Bulk Prepared by in-situ Hot Isostatic Pressing Method’,IEEE Trans. Appl. Supercond. 30 (2020) 6800406 (6 pages) (DOI: 10.1109/TASC.2020.2985355) (No. 281
paper)(I-27) Muralidhar Miryala, Sai Srikanth Arvapalli, Naomichi Sakai, Masato Murakami, Hidehiko Mochizuki,
Tomoyuki Naito, Hiroyuki Fujshiro, Milos Jirsa, Akira Murakami, and Jacques Noudem, “Complex Pulse
Magnetization Process and Mechanical Properties of Spark Plasma Sintered Bulk MgB2”,
Materials Science & Engineering B 273 (2021) 115390 (10 pages) (DOI: 10.1016/j.mseb.2021.115390)(No. 285 paper)(I-28) Y. Takahashi, T. Naito and H. Fujshiro, “Trapped field properties of MgB2 bulks prepared via an in-situ
infiltration-reaction process using refined boron powders”,
to be published in IEEE Trans. Appl. Supercond. (2022) (No. 289 paper)(I-29) Y. Takahashi, T. Naito and H. Fujshiro, “Critical current properties of an ex-situ MgB2/TiB2 sample
fabricated by spark plasma sintering using MgB2 powder containing TiB2”,
Submitted to Physica C (2022) (No. 291 paper)

J. 熱電変換材料の開発 10 編
(J-1) H. Fujishiro, K. Kusaka, M. Ikebe, H. Ogasawara and K. Noto, “Possibility of Ag2O+YBa2Cu3O7-X ceramics
for low temperature thermoelectric refrigeration”,
Cryogenics 34 (1994) Suppl. ICEC-15, pp. 231-234 (No. 25 paper)(J-2) N. Yoshida, T. Naito and H. Fujishiro, “Thermoelectric Properties of Li-Doped CuO”,
Jpn. J. Appl. Phys. 52 (2013) 031102 (5 pages) (No. 198 paper)(J-3) N. Yoshida, T. Naito and H. Fujishiro, “Thermoelectric properties of Li-doped Cu0.95-xM0.05LixO (M=Mn, Ni,
Zn)”,
MRS Online Proceedings 1490 (2013) pp. 69-73 (No. 202 paper)(J-4) Y.-C. Lai, H.-J. Tsai, C.-I. Hung, H. Fujishiro, T. Naito, W.-K. Hsu, “Carbon nanotubes enhanced Seebeckcoefficient and power factor of rutile TiO2”,
Phys. Chem. Chem. Phys. 17 (2015) pp. 8120-8124 (No. 220 paper)(J-5) R. Abe, H. Fujishiro and T. Naito, “Substitution effect of tetravalent and pentavalent elements onthermoelectric properties in In2O3-SnO2 system”,
Trans. Mat. Res. Soc. Jpn. 41 (2016) pp. 101-108 (No. 229 paper)21－ 19 －

(J-6) Shu Mizuno, Mamoru Ishizawa, Hiroyuki Fujishiro, Tomoyuki Naito, Hirokazu Katsui and Takashi Goto,“Ball milling effects for induced carriers and reduced grain size on thermoelectric properties in Bi1xSrxCuSeO (x = 0, 0.1)”,
Jpn. J. Appl. Phys. 55 (2016) 115801 (7 pages) (No. 236 paper)(J-7) Shu Mizuno, Hiroyuki Fujishiro, Mamoru Ishizawa, Tomoyuki Naito, Hirokazu Katsui and Takashi Goto,“Thermoelectric properties of LiCo1-xMxO2 (M=Cu, Mg, Ni, Zn) and comparison to LiyCoO2 and NayCoO2
systems”,
Jpn. J. Appl. Phys. 56 (2017) 021101 (6 pages) (DOI: 10.7567/JJAP.56.021101) (No. 243 paper)(J-8) Takamitsu Hara, Hiroyuki Fujishiro, Tomoyuki Naito, Akihiko Ito and Takashi Goto, “Optimized growth
condition of SnSe epitaxial films grown by pulsed laser deposition”,
Jpn. J. Appl. Phys. 56 (2017) 125503 (6 pages) (DOI: 10.7567/JJAP.56.125503) (No. 252 paper)(J-9) Mamoru Ishizawa, Hiroyuki Fujishiro, Tomoyuki Naito, Akihiko Ito and Takashi Goto, “Crystal orientation,
crystallinity, and thermoelectric properties of Bi0.9Sr0.1CuSeO epitaxial films grown by pulsed laser
deposition”,
Jpn. J. Appl. Phys. 57 (2018) 025502 (7papers) (DOI: 10.7567/JJAP.57.025502) (No. 254 paper)(J-10) Mamoru Ishizawa, Yuki Yasuzato, Hiroyuki Fujishiro, Tomoyuki Naito, Hirokazu Katsui and Takashi Goto,“Oxidation states and thermoelectric properties of BiCuSeO bulks fabricated under Bi or Se deficiencies in
the nominal composition”,
J. Appl. Phys. 123 (2018) 245104 (9 pages) (DOI: 10.1063/1.5034499) (No. 260 paper)

K. ⾼分⼦材料、磁性蓄冷材、その他の熱物性 9 編(K-1) H. Fujishiro, M. Ikebe, T. Kashima and A. Yamanaka, “Thermal Conductivity and Diffusivity of HighStrength Polymer Fibers”,
Jpn. J. Appl. Phys. 36 (1997) pp. 5633-5637 (No. 47 paper)(K-2) H. Fujishiro, M. Ikebe, T. Kashima and A. Yamanaka, “Drawing Effect on Thermal Properties of HighStrength Polyethylene Fibers”,
Jpn. J. Appl. Phys. 37 (1998) pp. 1994-1995 (No. 50 paper)(K-3) A. Yamanaka, T. Kitagawa, M. Tsutsumi, T. Kashima, H. Fujishiro, K. Ema, Y. Izumi and S. Nishijima,“Thermal Strain of High Strength Polyethylene Fiber in Low Temperature”,
J. Appl. Polym. Sci. 93 (2004) pp. 2918-2925 (No. 107 paper)(K-4) A. Yamanaka, H. Fujishiro, T. Kashima, T. Kitagawa, K. Ema, Y. Izumi, M. Ikebe and S. Nishijima,“Thermal Conductivity of High Strength Polyethylene Fiber in Low Temperature”,
J. Polym. Sci., Part B 43 (2005) pp. 1495-1503 (No. 114 paper)(K-5) A. Yamanaka, M. Yoshikawa, S. Abe, M. Tsutsumi, T. Oohazama, T. Kitagawa, H. Fujishiro, K. Ema, Y.
Izumi, S. Nishijima, “Effects of Vaper-Phase-Formaldehyde Treatments on Thermal Conductivity andDiffusivity of Ramie Fibers in the Range of Low Temperature”,
J. Polym. Sci., Part B 43 (2005) pp. 2754-2766 (No. 117 paper)(K-6) A. Yamanaka, S. Abe, M. Tsutsumi, T. Kitagawa, H. Fujishiro, K. Ema, Y. Izumi and S. Nishijima,“Thermal Conductivity of Ramie Fiber Drawn in Water in Low Temperature”,
J. Appl. Polym. Sci. 100 (2006) pp. 2196-2202 (No. 127 paper)(K-7) A. Yamanaka, Y. Izumi, T. Kitagawa, T. Terada, H. Hirahata, K. Ema, H. Fujishiro and S. Nishijima, “TheRadiation Effect on Thermal Strain of High Strength Ultra-High-Molecular-Weight Polyethylene Fiber by
g-Rays,J. Appl. Polymer Sci. 101 (2006) pp. 2619-2626 (No. 129 paper)22－ 20 －

(K-8) A. Yamanaka, Y. Izumi, T. Terada, K. Ema, M. Tsutsumi, M. Nakamura, T. Oohazama, T. Kitagawa, H.
Fujishiro, S. Abe and S. Nishijima, “Radiation Effect on the Thermal Conductivity and Diffusivity of Ramie
Fiber in a Range of Low Temperatures by g-Rays”,
J. Appl. Polymer Sci. 101 (2006) pp. 5007-5018 (No. 137 paper)(K-9) A. Yamanaka, Y. Izumi, T. Kitagawa, T. Terada, H. Hirahata, K. Ema, H. Fujishiro and S. Nishijima, “The
Effect of g-Irradiation on Thermal Strain of High Strength Polyethylene Fiber at Low Temperature”,
J. Appl. Polym. Sci. 102 (2006) pp. 204-209 (No. 138 paper)

L. パーコレーション伝導、熱伝導率のモデル解析 4 編(L-1) M. Ikebe, H. Fujishiro, M. Matsukawa, F. Tatezaki, H. Ogasawara, K. Noto, K. Michishita and Y. Kubo, “A
Model Analysis of the Thermal Conductivity of Ag-doped Bi-Sr-Ca-Cu-O Superconducting Oxide”,
Jpn. J. Appl. Phys. 33 (1994) pp. 2004-2007 (No. 20 paper)(L-2) H. Fujishiro, M. Ikebe, Y. Minato, H. Ogasawara and K. Noto, “Model analyses of thermal conductivity andpurity of doped Ag in Ag+YBa2Cu3O7”,
Superlattices and Microstructures 21 (1997) pp. 349-352 (No. 43 paper)(L-3) M. Ikebe and H. Fujishiro, “TRANSPORT AND THERMOELECTRIC PROPERTIES OF YBa2Cu3O7-d-Ag
PERCOLATION SYSTEM”,
Advances in Science and Technology 23 (1999) pp. 445-452 (No. 63 paper)(L-4) M. Ikebe and H. Fujishiro, “Percolation Analyses on Transport Properties of YBa2Cu3O7-d-Ag System,
J. Low Temp. Phys. 117 (1999) pp. 1289-1293 (No. 64 paper)

M. 多層膜超伝導体の研究 18 編
(M-1) M. Ikebe, Y. Obi, H. Fujishiro and H. Fujimori, “A Study of the Flux Pinning Anisotropy in Nb/Al2O3
Superconducting Multilayers”,
Jpn. J. Appl. Phys. 32 (1993) pp. 55-59 (No. 7 paper)(M-2) Y. Obi, M. Ikebe, H. Fujishiro and H. Fujimori, “Pinning Mechanism Studies on the Nb /Ag
Superconducting Multilayer”,
Jpn. J. Appl. Phys. 32 (1993) pp. 1952-1955 (No. 8 paper)(M-3) M. Ikebe, Y. Obi, H. Fujishiro and H. Fujimori, “Dimensional Crossover in the Nb/Al2O3 JosephsonCoupled Multilayers”,
J. Phys. Soc. Jpn. 62 (1993) pp. 3680-3685 (No. 9 paper)(M-4) Y. Obi, M. Ikebe, H. Fujishiro, S. Takahashi and H. Fujimori, “Superconducting Properties of NbTi BasedMultilayers”,
J. Low Temp. Phys. 96 (1994) pp. 1-18 (No. 22 paper)(M-5) Y. Obi, M. Ikebe, H. Fujishiro and H. Fujimori, “Anomalous Tc behavior in NbTi/Nb superconducting
multilayers”,
Physica C 235-240 (1994) pp. 2561-2562 (No. 29 paper)(M-6) M. Ikebe, T. Naito, H. Fujishiro, K. Noto, N. Kobayashi and K. Mori, “Lattice thermal conductivity of Nbbased alloy superconductors and phonon scattering by electrons”,
Physica B 219&220 (1996) pp. 80-82 (No. 31 paper)(M-7) M. Ikebe, Y. Obi, H. Fujishiro and H. Fujimori, “Flux Pinning and Dimensionality of Superconductivity in
Multilayers”,
Czech. J. Phys. 46 (1996) Suppl. S2, pp. 719-720 (No. 37 paper)(M-8) M. Ikebe, H. Fujishiro, Y. Obi, H. Fujimori and Y. Kamiguchi, “Pauli Paramagnetic Effect and Parallel
Critical Field of Nb/Al2O3 Multilayers”,
Superlattices and Microstructures 21 (1997) Suppl. A. pp. 153-156 (No. 42 paper)23－ 21 －

(M-9) Y. Obi, H. Fujimori, M. Ikebe and H. Fujishiro, “Flux pinning in NbTi-based multilayers”,
Superlattices and Microstructures 21 (1997) pp. 423-426 (No. 45 paper)(M-10) M. Ikebe, H. Fujishiro and H. Iwasaki, “Magnetic structure and dipolar interaction in antiferromagnetic
superconductor BCT-ErRh4B4”,
J. Mag. Mag. Mater. 177-181 (1998) pp. 549-550 (No. 49 paper)(M-11) M. Ikebe, H. Fujishiro, Y. Obi, H. Fujimori and S. Morohashi, “On anomalous temperature dependence of
Hc2⊥ in natural and artificial layer superconductors”,
Physica C 317-318 (1999) pp. 142-148 (No. 58 paper)(M-12) Y. Obi, M. Ikebe, H. Fujishiro and H. Fujimori, “Flux pinning characteristics in NbTi/Nbsuperconductor/superconductor multilayers”,
Physica B 284-288 (2000) pp. 857-858 (No. 67 paper)(M-13) Y. Obi, M. Ikebe, H. Fujishiro, K. Takanaka and H. Fujimori, “Synthetic Analyses of Tc and Hc2 of
NbTi/Nb Superconductor/Superconductor Superlattice”,
phys. stat. sol. (b) 223 (2001) pp. 799-809 (No. 72 paper)(M-14) Y. Obi, M. Ikebe and H. Fujishiro, “Pauli paramagnetic effect and spin-orbit scattering time in Nb/Al2O3
superconducting multilayers”,
Physica B 329-333 (2003) pp.1423-1424 (No. 93 paper)(M-15) Y. Obi, H. Fujishiro and M. Ikebe, “Evidence for zero and p phase from superconducting transition
temperature in Nb/Co superconducting multilayers”,
J. Mag. Mag. Mat. 272-276 (2004) pp. e1087-e1088 (No. 102 paper)(M-16) Y. Obi, M. Ikebe and H. Fujishiro, “Repulsive Flux Pinning Force in NbTi/Nb Superconductor/Superconductor Multilayers”,
J. Low Temp. Phys. 137 (2004) pp. 125-137 (No. 108 paper)(M-17) Y. Obi, M. Ikebe and H. Fujishiro, “Evidence for Zero- and p-Phase Order Parameters of Superconducting
Nb/Co Tri- and Pentalayers from the Oscillatory Behavior of the Transition Temperature”,
Phys. Rev. Lett. 94 (2005) pp. 057008-1–4 (No. 113 paper)(M-18) Y. Obi, M. Ikebe and H. Fujishiro, “Analyses of the pinning mechanism for the superconductor/normalmetal and superconductor/superconductor multilayers”,
J. Superconductivity and Novel Magnetism 19 (2006) pp. 117-123 (No. 139 paper)

N. Si, GaAs, ZnSe などの半導体材料に関する研究 11 編
(N-1) H. Fujishiro and S. Furukawa, “GROWTH MODEL OF HYDROGENATED MICROCRYSTALLINE
SILICON PREPARED BY RF SPUTTERING IN PURE HYDROGEN”,
Solid State Commun. 73 (1990) pp. 835-838 (No. 1 paper)(N-2) 藤代博之、古川昌司、⼭崎義武、「⽔素プラズマスパッター法による微結晶 Si:H の成⻑モデル」、
⽇本化学会誌 1990-5 (1990) pp.495-498 (No. 2 paper)(N-3) F. Sakurai, H. Fujishiro, K. Suto and J. Nishizawa, “ZnSe epitaxial growth by the temperature difference
method under controlled vapor pressure (TDM-CVP) using Se solvent,”
J. Cryst. Growth 112 (1991) pp. 153-159 (No. 3 paper)(N-4) H. Fujishiro and S. Furukawa, “Dependence of microcrystal size on hydrogen gas pressure in silicon-based
alloys prepared by reactive laser ablation”,
J. Phys.: Condens. Matter 3 (1991) pp. 7539-7543 (No. 4 paper)24－ 22 －

(N-5) S. Furukawa, M. Obana, M. Tamura and H. Fujishiro, “ORIENTATION OF ONE-DIMENSIONALSILICON BACKBONE IN TERNARY Si:C:H FILMS PREPARED BY EVAPORATION OF
ORGANOPOLYSILANE”,
Solid State Commun. 84 (1992) pp. 475-478 (No. 5 paper)(N-6) S. Furukawa, M. Nagatomo, H. Kokuhata, K. Takeuchi, H. Fujishiro and M. Tamura, “Effects of iodine
doping on electrical and optical properties of ternary Si:C:H films prepared by evaporation oforganopolysilane”,
J. Phys.: Condens. Matter 4 (1992) pp. 8357-8362 (No. 6 paper)(N-7) H. Fujishiro, S. Furukawa, I. Takahashi and T. Kuwashima, “Structure and Electrical Properties of LowPressure-Plasma-Sprayed Silicon-Based Materials”,
J. Ceram. Soc. Jpn. 102 (1994) pp. 1-4 (No. 15 paper)(N-8) J. Nishizawa, M. Motozawa, Y. Oyama, K. Dezaki, H. Fujishiro and K. Suto, “Photocapacitance
Measurement on Intentionally Undoped n-type Ga0.9Al0.1As Grown by Stoichiometry Control Method”,
Jpn. J. Appl. Phys. 33 (1994) pp. 1753-1758 (No. 19 paper)(N-9) M. Ikebe, M. Matsukawa, H, Fujishiro, N. Yoshimoto, M. Yoshizawa and K. Noto, “Thermal Conductivity
in the ab-Plane of the Organic Conductor a-(BEDT-TTF)2I3”,
J. Phys. Soc. Jpn. 65 (1996) pp. 651-651 (No. 35 paper)(N-10) D. H. Yoon, I. Agung, H. Fujishiro and M. Yoshizawa, “Exact Observation of Oxygen Radicals by Voltage
Locked Loop Method for the Application to Molecular Beam Epitaxial Growth”,
Materials Transactions, JIM 37 (1996) pp. 898-901 (No. 36 paper)(N-11) Abdusalam Ismayil, Taichi Nakamura, Ryosuke Kamiya, Mitsuteru Nakamura, Yoshiki Nakanishi,
Tomoyuki Naito, Hiroyuki Fujishiro, Takao Watanabe, Gaku Sawada, Masahiro Toita, Katsuhiko
Takegahara, and Masahito Yoshizawa, “Effect of Carrier Doping on Physical Properties of A-Site Ordered
Perovskite CaCu3Ti4O12”,
J. Phys. Soc. Jpn. 80 (2011) SA113 (No. 188 paper)

O. 博⼠学位論⽂(O-1) 藤代博之：「蒸気圧制御下における相図の研究」東北⼤学（⼯第 987 号）

25－ 23 －

３．代表的論⽂リスト 10 編
1. (D-1) 藤代博之、内藤智之、池部 学、能登宏七、「低温における熱拡散率と熱伝導率の同⼀セッテ
ィング測定」、
低温⼯学 28 (1993) pp. 533-539 (No. 10 paper)
2. (F-17) Hiroyuki Fujishiro, Tatsuya Tateiwa, Atsushi Fujiwara, Tetsuo Oka and Hidemi Hayashi, “Higher
trapped field over 5 Tesla on HTSC bulk by modified pulse field magnetizing”,
Physica C 445-448 (2006) pp. 334-338 (No. 134 paper)
3. (G-1) H. Fujishiro and T. Naito, “Simulation of temperature and magnetic field distribution in superconducting
bulk during pulsed field magnetization”,
Supercond. Sci. Technol. 23 (2010) 105021 (8 pages) (No. 174 paper)
4. (A-41) H. Fujishiro, T. Naito, S. Ogawa, K. Nitta, J. Hejtmanek, K. Knizek and Z. Jirak, “Valence shift of Pr
ion from 3+ to 4+ in (Pr1-yYy)0.7Ca0.3CoO3 estimated by X-ray absorption spectroscopy”,
J. Phys. Soc. Jpn. 81 (2012) 064709 (5 pages) (No. 189 paper)
5. (A-48) Y. Noda, H. Fujishiro, T. Naito, A. Ito, T. Goto, J. Hejtmanek and Z. Jirak, “Electrical resistivity
anomaly in (Pr1-yMy)1-xCaxCoO3 epitaxial films (M = Y, Gd) fabricated by pulsed laser deposition”,
AIP Advances 6 (2016) 025318 (9 pages) (No. 232 paper)
6. (H-1) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A new concept of hybrid trapped field magnet lens
(HTFML)”,
Supercond. Sci. Technol. 31 (2018) 044005 (9 pages) (No. 257 paper)
7. (H-3) Sora Namba, Hiroyuki Fujishiro, Tomoyuki Naito, Mark D Ainslie, Keita Takahashi, “Experimental
realization of a Hybrid Trapped Field Magnet Lens (HTFML) using a GdBaCuO magnetic lens and MgB2
bulk cylinder”,
Supercond. Sci. Technol. Letter 32 (2019) 12LT03 (7 pages) (No. 271 paper)
8. (I-25) Tatsuya Hirano, Yuhei Takahashi, Sora Namba, Tomoyuki Naito and Hiroyuki Fujishiro, “A record-hightrapped field of 1.61 T in MgB2 bulk comprised of copper plates and soft iron yoke cylinder using pulsedfield magnetization”,
Supercond. Sci. Technol. 33 (2020) 085002 (10 pages) (No. 276 paper)
9. (H-8) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A conceptual study of a high gradient trapped fieldmagnet (HG-TFM) providing toward a quasi-zero gravity space on Earth”,
Supercond. Sci. Technol. 34 (2021) 035001 (13 pages) (No. 283 paper)
10. (H-9) K. Takahashi, H. Fujishiro, S. Namba and M. D. Ainslie, “Experimental realization of an all(RE)BaCuO hybrid trapped field magnet lens generating a 9.8 T concentrated magnetic field from a 7 T
external field”,
Supercond. Sci. Technol. 34 (2021) 05LT02 (9 pages) (No. 284 paper)26－ 24 －

４．研究論⽂の分析、概要27－ 25 －

それ以外

28－ 26 －

29－ 27 －

30－ 28 －

主な学術雑誌の論⽂の件数とインパクトファクター(IF)
論文数IF (2022.2.10 現在)

Superconductor Science and Technology

46

3.219

Physica C: Superconductivity & Its applications

40

1.241

IEEE Trans. Appl. Supercond.

34

1.704

Physica B: Condensed Matter

22

2.436

J. Physical Society of Japan

19

1.828

Japanese Journal of Applied Physics

13

1.480

Journal Physics Conference Series

11

0.547

J. Low Temp. Physics

7

1.570

J. Mag. Mag. Matter

6

2.993

J. Applied Physics

6

2.546

Cryogenics

6

2.226

Physical Review B

3

4.036

雑誌名

主な共著者との論⽂の件数
共著者

共著論文数

Tomoyuki Naito

130

Manabu Ikebe

90

Mark D Ainslie

37

Keita Takahashi

24

Tetsuo Oka

28

Yousuke Yanagi

17

Jiri Hejtmanek13－ 29 －

５．国際会議発表論⽂(Koku-1) H. Fujishiro, K. Kusaka, M. Ikebe and K. Noto, “Use of Bi-2223 Superconducting Tapes Sheathed with
Ag-Au Alloys for a Passive Thermoelement”,
Proceedings of the 12th International Conference on Thermoelectrics (XII ICT) Editied by K. Matsuura,(Yokohama, Japan, Nov. 9-11, 1993) pp. 169-174, 1993
(Koku-2) H. Fujishiro, M. Ikebe, H. Ogasawara, K. Noto, K. Michishita and Y. Kubo, “Anisotropic Transport
Properties of Ag-Bi2212 Prepared by Floating Zone Method”,
Proceedings of the 9th US-Japan Workshop on High-Field Superconducting Materials, Wires andConductors and Standard Procedures for High-Field Superconducting Wires Testing, (Kyoto, Japan, March
13-15, 1995) pp. 61-64, 1995
(Koku-3) T. Sasaoka, K. Nomura, J. Sato, M. Seido, H. Kumakura, K. Togano, H. Maeda, J. Shimoyama, H.
Fujishiro, M. Ikebe and K. Noto, “Bi-System Oxide Superconducting Tapes Based on Silver-Alloy for Power
Current Leads”,
Proceedings of International Symposium on Superconductivity (ISS’92) pp. 729-731, 1993
(Koku-4) H. Fujishiro and M. Ikebe, “Heat Transport Anomalies around Ferromagnetic and Charge-order
Transitions in La1-XCaXMnO3”,
Proceedings of International Symposium on Physics in Local Lattice Distortions (Physics in Local LatticeDistortions, edited by H. Oyanagi and A. Bianconi (American Institute of Physics) (Tsukuba, Japan, July
23-26, 2000) pp. 433-436, 2001
(Koku-5) H. Nakane, S. Yamazaki, H. Fujishiro, T. Yamaguchi, S. Yoshizawa, T. Numazawa and M. Okamura,“Low Temperature Properties of HoSb, DySb and GdSb”,
Proceedings of the 11th International Cryocooler Conference (Colorado, USA, 2000.6.20-22), pp451-457,
2000(Koku-6) H. Nakane, S. Yamazaki, H. Fujishiro, S. Yoshizawa, T. Numazawa and M. Okamura, “Low
Temperature Properties of Rare-Earth and Sb Compounds”,
Proceedings of the Sixth Joint Sino-Japanese Seminar on Cryocooler and its Applications (JSJS-6)(Lanzhou, China, 2000. 8.20-24) pp. 137-142, 2000
(Koku-7) H. Nakane, S. Nishijima, H. Fujishiro, T. Yamaguchi, S. Yoshizawa and S. Yamazaki, “THERMALPROPERTIES OF EPOXY RESINS AT CRYOGENIC TEMPERATURES”,
Advanced in Cryogenic Engineering (Proceedings of the International Cryogenic Materials Conference –ICMC), Vol.48, pp.211-217, 2002
(Koku-8) H. Fujishiro, Y. Fujine, J. Hejtmanek, D. Sedmidubsky, A. Maignan and C. Martin, “Search for p-typeoxide thermoelectrics –cobaltites—“,
Proceedings of 21th International Conference on Thermoelectrics (ICT ’03) IEEE, (La Grande-Motte,France, August 17-21, 2003), pp. 192-195, 2004 No.83(Koku-9) H. Fujishiro, Y. Fujine, Y. Kashiwada, M. Ikebe and J. Hejtmanek, “Enhanced Thermoelectric Properties
at X~0.1 in La1-XSrXCoO3 and La1-XSrX(Co1-YMY)O3 (M = Cr, Co)”, No.82
Proceedings of 21th International Conference on Thermoelectrics (ICT ’03) IEEE, (La Grande-Motte,France, August 17-21, 2003), pp. 235-238, 2004
(Koku-10) H. Fujishiro, Y. Suzuki, Y. Fujine and M. Ikebe, “Size Effect of A-site Cation on n-type Thermoelectric
Properties in CaMnO3-based System”,
Proceedings of 22th International Conference on Thermoelectrics (ICT ’04) IEEE, (Adelaide, Australia,
July 24-29, 2004), 200532
－ 30 －

(Koku-11) H. Fujishiro, Y. Fujine, M. Ikebe and J. Hejtmanek, “Influence of Co-site Substitution on
Thermoelectric Properties in La1-XSrXCoO3”,
Proceedings of 22th International Conference on Thermoelectrics (ICT ’04) IEEE, (Adelaide, Australia,
July 24-29, 2004), 2005
(Koku-12) Y.-H. Lee, T. Koyanagi and H. Fujishiro, “Transport Properties of Bi-Sb Sintered Alloys Prepared by
Spark Plasma Sintering”,
Proceedings of 22th International Conference on Thermoelectrics (ICT ’04) IEEE, (Adelaide, Australia,
July 24-29, 2004), 200533
－ 31 －

６．著書(Book-1) “Superconductivity –Recent Developments and New Production Technologies—“, Edited by Muralidhar
Miryala, Nova Publishers Inc., New York (ISBN: 978-1-62257-137-6), Chapter 12, “Pulsed Field
Magnetization on Superconducting Bulk and the Applications as a Strong Magnet” pp. 241-257（分担執筆）2012(Book-2) “Research, Fabrication and Applications Bi-2223 HTS Wires” Edited by Kenichi Sato, World Scientific
Series in Applications of Superconductivity and Related Phenomena, Vol. 1, (ISSN 2424-8533), Chapter
1.7, “Thermal Properties of Bi-2223 Wires” pp. 73-103（分担執筆）2016(Book-3) “Numerical Modelling of Bulk Superconductor Magnetization”, Mark Ainslie and Hiroyuki Fujishiro,
IOP Publishing, Bristol, UK (ISBN: 978-0-7503-1332-2) 202034
－ 32 －

７．解説、総説、新聞記事(kai-1) 能登宏七、松川倫明、藤代博之、「固体物性解析技術—超伝導測定法—」まてりあ, Vol. 36, No. 4,
pp. 330-336, 1997
(kai-2) 「安価な強力磁石開発」《岩手日報 2005,8.28 朝刊１面掲載》(kai-3) 藤代博之、「超強力なバルク超伝導磁石の開発と産業応用」《2006 年：岩手大学工学部同窓会誌（北杜）「研究の窓」寄稿》(kai-4) 藤代博之「バルク超電導体のパルス着磁技術の動向と熱物性データベース」《2006 年：電気学会
研究会 ASC-07-06》(kai-5) 藤代博之、「パルス着磁法による５Ｔを越える超伝導バルク磁石の実現」《2007 年：まぐね vol. 2
pp. 28-34》(kai-6) 藤代博之、「超伝導バルク磁石装置と産業応用」《2007 年：化学工業 vol.58, no.6, pp. 423-427》(kai-7) 藤代博之、「バルク超電導体の着磁現象」《2011 年：低温工学・超伝導学会誌 vol. 46, pp. 81-88 解説》(kai-8) 藤代博之、「地方支部活動の必要性（東北・北海道支部支部長に就任して）」《2019 年：低温工学・超伝導学会誌サロン, Vol. 54 p. 492》
(kai-9) 藤代博之、高橋圭太、「擬似微小重力環境を実現するハイブリッド超電導バルク磁石装置の開発と磁気浮上応用」《2021 年：化学工業 vol. 72, no.12, pp. 781-785》(Kai-10) 内藤智之、藤代博之、「MgB2 超伝導バルク磁石の現状と展望」《2021 年：低温工学・超伝導学
会誌 vol. 56, pp. 309-316 テーマ解説》35－ 33 －

８．特許出願、取得(Pat-1) 「バルク超伝導体の熱的安定化方法」
出願日および出願番号：2003 年 4 月 16 日 （特願 2003-112116）（特開 2004-319797）
発明者：藤代博之、岡 徹雄、横山和哉
出願人：科学技術振興事業団、アイシン精機㈱(Pat-2) 「バルク超伝導体の熱的安定化方法」
出願日および出願番号：2003 年 4 月 16 日 （特願 2003-112117）（特開 2004-319798）
発明者：藤代博之、岡 徹雄、横山和哉
出願人：科学技術振興事業団、アイシン精機㈱(Pat-3) 「バルク超伝導体の着磁方法」
出願日および出願番号：2004 年 3 月 31 日 （特願 2004-106330）（特開 2005-294471）
発明者：藤代博之、岡 徹雄、横山和哉
出願人：科学技術振興事業団、アイシン精機㈱(Pat-4) 「断熱性セルロース繊維」
出願日および出願番号：2005 年 5 月 20 日 （特願 2005-147738）（特開 2006-322115）
発明者：山中淳彦、安倍俊三、堤 正幸、大峡岳志、吉川雅敏、西嶋茂宏、泉 佳信、寺田 隆
哉、藤代博之
出願人：東洋紡績㈱(Pat-5) 「熱伝導性セルロース繊維」
出願日および出願番号：2005 年 5 月 20 日 （特願 2005-147739）（特開 2006-322116）
発明者：山中淳彦、安倍俊三、堤 正幸、大峡岳志、吉川雅敏、西嶋茂宏、泉 佳信、寺田 隆
哉、藤代博之
出願人：東洋紡績㈱(Pat-6) 「バルク超伝導体のパルス着磁⽅法及び超伝導磁⽯装置」
出願⽇および出願番号：2005 年 5 ⽉ 30 ⽇ (特願 2005-156956)（特開 2006-332499）
発明者：藤代博之、⾦⼭雅彦、岡 徹雄
出願⼈：岩⼿⼤学、アイシン精機㈱(Pat-7) 「薄膜の製造⽅法」
出願⽇：2007.9.19 (特願 2007-242624)
発明者：吉本則之、藤代博之、⼩川 智
特許権者：国⽴⼤学法⼈岩⼿⼤学
登録⽇：2013.5.24 (特許第５２３４２９号)(Pat-8) 「磁場中有機単結晶薄膜作成法及び作成装置」
出願⽇：2010.3.1 (特願 2010-044727)
発明者：吉本則之、荒⽊俊⾏、藤代博之
特許権者：国⽴⼤学法⼈岩⼿⼤学
登録⽇：2014.8.8 (特許第５５９０６５９号)(Pat-9) 「有機半導体材料並びに有機半導体装置及びその製造⽅法」
出願⽇：2010.8.18 (特願 2010-182792)
発明者：⼩川 智、吉本則之、藤代博之
特許権者：国⽴⼤学法⼈岩⼿⼤学
登録⽇：2015.4.10 (特許第５７２５４９４号)

36－ 34 －(Pat-10)「超電導磁場発⽣素⼦」
出願⽇：2017/5/23（特願 2017-101661）（特開 2018-198245）
発明者：柳 陽介、伊藤佳孝、藤代博之、内藤智之
特許権者：株式会社アイシン
登録⽇：2021.10.5 (特許第６９５５１９２号)(Pat-11) 「ハイブリッド型超電導バルク磁⽯装置」
出願⽇：2018/1/17（特願 2018-005677）（特開 2019-125710）
特許査定：2021/12/17
発明者：藤代博之、髙橋圭太
特許権者：国⽴⼤学法⼈岩⼿⼤学
登録⽇：2022/1/11 (特許第７００６２９１号)(Pat-12) 「ハイブリッド型超電導バルク磁⽯装置とその着磁⽅法」
出願⽇：2019/11/28（特願 2019-214998）（特開 2021-86927）
発明者：藤代博之
出願⼈：国⽴⼤学法⼈岩⼿⼤学(Pat-13) 「⾼磁気勾配型超電導バルク磁⽯装置」
出願⽇：2020/10/28、（特願 2020-180228）
発明者：髙橋圭太、藤代博之
出願⼈：国⽴⼤学法⼈岩⼿⼤学37－ 35 －

９．表彰、受賞(Hyo-1) 低温⼯学協会褒賞、優良発表賞：「REBaCuO バルク超伝導体の熱的性質(RE=Dy, Gd, Ho, Nd)」
（平成 17 年）(Hyo-2) Top Cited Article 2005-2010 (Physica C: Superconductivity and its Applications”, ELSEVIER,
Hiroyuki Fujishiro, Tatsuya Tateiwa, Atsushi Fujiwara, Tetsuo Oka and Hidemi Hayashi “Higher trappedfield over 5 Tesla on HTSC bulk by modified pulse field magnetizing”, Physica C 445-448 (2006) pp.
334-338(Hyo-3) Superconductor Science and Technology (SUST)誌 30th anniversary collection として選定される。
”Modelling of bulk superconductor magnetization”, M D Ainslie and H Fujishiro 2015 Supercond. Sci.
Technol. 28 053002(Hyo-4) IOP (Institute of Physics Publishing: 英国物理学会出版)誌の trusted reviewer として選定される。
2020 年

38－ 36 －

１０．国際会議出席発表（本⼈発表分）（★：招待講演、☆：⼝頭発表、△：short oral+poster、□：poster）
Year
1993 (H5)

海外で開催された国際会議及び、講演★MT-13(Victoria, Canada) (9.21-27)“Low Thermal Conductive Bi-2223 Tapes
Sheathed with Ag-Au Alloys”

1994 (H6)□15th ICEC (Genova, Italy) (6.7-10)“Possibility of Ag2O+YBa2Cu3O7-X ceramics for
low temperature thermoelectric refrigeration”

1995 (H7)1996 (H8)□M2S (Grenoble, France) (7.7-11)“Thermal Conductivity of Bi-2212 Single
Crystals Prepared by TSFZ Method”“Phonon Thermal Diffusivity and Conductivityof Oxygen Deficient YBa2Cu3O7”☆WTC'96 (Budapest, Hungary) (7.7-10)“Model analyses of thermal conductivity andpurity of doped Ag in Ag+YBa2Cu3O7”

国内で開催された国際会議△ICT12 (Yokohama) (11.9-11)“Use of Bi2223 Superconducting Tapes
Sheathed with Ag-Au Alloys for a
Passive Thermoelement”☆Jpn.-US workshop (Kyoto)□Phonons'95 (Sapporo)“Thermal Conductivity and Diffusivityof Nd2-XCeXCuO4”□MOS'96 (Karlsruhe, Germany) (8.1-7)“Thermal conductivity and phonon scattering
mechanisms in La1-xMxCuO4”

1997 (H9)1998 (H10)1999 (H11)□LT21 (Prague, Czech) (8.8-14)“Effect of Y-site and Ba-site Substitution on
Thermal Properties of YBa2Cu3O7-d”“Proposal of Three Terminal Method for Low
Temperature Thermal Diffusivity Measurement”□ICM'97 (Cairns, Australia) (7.27-8.1)“Thermal conductivity and phonon scattering of
La1-XSrXMnO3”□CIMTEC'98 (Florence, Italy) (6.18-28)“THERMAL CONDUCTIVITY OF T*-PHASE(Nd1-x-yCexSry)2CuO4 OXIDESUPERCONDUCTORS”“ULTRASONIC AND PHONON THERMAL
TRANSPORT STUDIES ON YBa2Cu3O7-d
OXIDE SUPERCONDUCTORS”☆Phonons'98 (Lancaster, England) (7.26-31)“Two-level-like anomalous phonon scattering in
La1-XSrXMnO3 and La2-XSrXCuO4”□MOS'99 (Stockholm, Sweden) (7.28-8.2)“Enhanced Phonon Scattering below Tc Caused byZn and Ni Substitution in La1.85Sr0.15CuO4”
39－ 37 －□SCES'99 (Nagano) (8.24-27)
First-order-like ferromagnetic transitionin (La1-yPry)1-x(Ca1-zSrz)xMnO3(X~0.25)”

□LT22 (Helsinki, Finland) (8.4-11)
Sound Velocity Anomaly Related to Charge
Ordering in La1-xCaxMnO3”☆JARCAT Workshop (Kyoto) (5.31)“Sound Velocity Anomalies Related toCharge Ordered Transition in La1xCaxMnO3 (0<x<1)”

2000 (H12)△LLD2k (Tsukuba) (7.23-26)“Heat Transport Anomalies aroundFerromagnetic
andCharge-order
Transitions in La1-xCaxMnO3”

2001 (H13)2002 (H14)2003 (H15)2004 (H16)□Phonons2001 (Dartmouth, USA) (8.12-17)“Thermal diffusivity of La1-XCaXMnO3 up to
1200 K”□ISS2000 (Tokyo) (10.14)“Thermal contact resistance between
high-Tc superconductor and copper”☆IMR workshop (Sendai) (5.22)“Charge/Orbital Order Fluctuation andLattice Softening in La1-xCaxMnO3”□MT-17 (Genova, Swiss) (9.24-27)“Thermal Conductivity, Thermal Diffusivity and
Thermoelectric Power of Sm-Based Bulk
Superconductors”△Orbital2001 (Sendai) (9.11-13)“Heat Transport Enhancement in
Ferromagnetic Metallic Phase of La1XBaXMnO3”□SCES'02 (Kraków, Poland) (7.8-15)“THERMAL TRANSPORT IN
FERROMAGNETIC La1-XAEXMnO3 WITHLARGE DIVALENT IONS”□LT23 (Hiroshima) (August)“Co Site Substitution Effect on
Thermoelectric Properties in Na(Co1XMX)2O4 (M=Ni, Fe, Mn, Cu)”

★チェコ科学アカデミー講演(7.16)□ISS2002 (Yokohama)“Thermal conductivity of YBaCuO
bulk superconductors under appliedfield: effect of content and size of Y211
phase”☆MT-18 (Morioka) (10.21)“Flux Motion Studies by means ofTemperature Measurement in
Magnetizing Processes for HTSC
Bulks”

⽂部省短期在外研究員（チェコ科学アカデミー）(2003.7.26~9.26)□ICM'03 (Roma, Italy) (7.27-31)“Thermal conductivity and magnetism in (Ca1XSrX)MnO3”☆ICT2003 (La Grande-Motte, France) (8.17-21)“Search for p-type Oxide Thermoelectrics –Cobaltites”“Enhanced Thermoelectric Properties at X~0.1 in
La1-XSrXCoO3 and La1-XSrX(Co1-YMY)O3 (M=Cr,Cu)”□ICT2004 (Adelaide, Australia) (7.24-31)“Influence of Co-site Substitution on
Thermoelectric Properties in La1-xSrxCoO3”“Size Effect of A-site Cation on n-type
Thermoelectric Properties in CaMnO3-based
System”
40－ 38 －☆ISS2003 (Tsukuba) (10.27)“Estimation of generated heat in pulse
field magnetizing for SmBaCuO bulk
superconductor”★ISS2004 (Niigata) (11.16)“Approach from temperature
measurement to trapped fieldenhancement in HTSC bulks by pulse
field magnetizing”“Database for thermal and mechanicalproperties of REBaCuO bulks”□ASC2004 (Jacksonville, U.S.A) (10.2-11)“Effect of Metal Ring Setting outside HTSC Bulk
Disk on Trapped Field and Temperature Rise in
Pulse Field Magnetizing”
2005 (H17)□SCES’05 (Wien, Austria) (7.28-31)“Anomalous Sound Velocity Behavior of La1XCaXMnO3 (X~0.48) in Applied Field”“Thermal Conductivity Anomaly in
La0.52Ca0.48MnO3 under Applied Field”□EUCAS2005 (Wien, Austria) (9.12-15)“Trapped Field over 4 Tesla on GdBaCuO Bulk
by Pulse Field Method and Magnetizing
Mechanis□MT19 (Genova, Italy) (9.19-23)“Low-Thermal-Conductive DyBaCuO Bulk
Superconductor for Current Lead Application”

2006 (H18)★チェコ科学アカデミー講演(9.11)

2007 (H19)☆6th PASREG (Cambridge, England) (9.11-18)“Possible Explanation for Trapped Field
Enhancement on REBaCuO Bulk by Modified
Multi-pulse Technique with Stepwise Cooling(MMPSC)”

2008 (H20)☆ASC2008 (Chicago, USA) (8.17-23)“Pulsed Field Magnetization for GdBaCuO Bulk
with Stronger Pinning Characteristics”

2009 (H21)□EUCAS2009 (Dresden, Germany) (9.12-20)“Highly efficient magnetic separation using fivealigned superconducting bulk magnet”★チェコ科学アカデミー講演 (9.20)“Recent research progresses of Cobaltites andManganites in Iwate”

2010 (H22)2011 (H23)□ASC2010 (Washington DC, USA) (8.1-10)“Analysis of Temperature and Magnetic Field
Distribution in Superconducting Bulk during
Pulsed Field Magnetization”□EUCAS2011 (Den Hague, The Netherland)(9.17-25)“Three-dimensional simulation of magnetic flux
dynamics and temperature rise in HTSC bulk
during pulsed field magnetization”★チェコ科学アカデミー講演 (9.17)

41－ 39 －☆PASREG (Tokyo University ofMarine Science and Technology）(10.20)“Thermal Conductivity and
Thermoelectric Power of DyBaCuO
Bulk Superconductor”☆ISS2005 (Tsukuba) (10.24-26)“Higher trapped field over 5 Tesla on
HTSC bulk by modified pulse fieldmagnetizing”☆ISS2006 (Nagoya) (10.30-11.2)“Importance of initial ‘‘M-shaped’’
trapped field profile in a two-stage
pulse field magnetization (MMPSC)
method”□ISS2007 (Tsukuba) (11.5-7)“Trapped field characteristics on f 65
mm GdBaCuO bulk by modified multipulse technique with stepwise cooling(MMPSC)”□ISS2008 (Tsukuba) (10.27-29)“Enhancement of total trapped fluxes
on f65 mm GdBaCuO bulk by multipulse techniques”☆ISS2009 (Tsukuba) (11.1-3)“Temperature measurements in small
holes drilled in superconducting bulk
during pulsed field magnetization”□ISS2010 (Tsukuba) (10.31-11.2)“Simulation of flux dynamics in asuperconducting bulk magnetized bymulti-pulse”

2012 (H24)☆ASC2012 (Portland, USA) (10.9-13)“Numerical Simulation of Trapped Field andTemperature Rise in MgB2 Bulks Magnetized byPulsed Field”★⼤連理⼯⼤講演(6.12-13)

2013 (H25)2014 (H26)2015 (H27)□EUCAS2013 (Genova, Italy) (9.15-20)“Trapped magnetic field between double stacked
MgB2 bulks magnetized by pulsed field”★チェコ科学アカデミー講演(9.22)“Recent research progresses of Cobaltites andManganites in Iwate”☆ASC2014 (Charlotte, USA) (8.9-18)“Recent progress of MgB2 bulk magnets
magnetized by pulsed field”★Saskatchewan ⼤講演 (12.1-3)☆UK-Japan workshop (Cambridge, England)(4.11-19)“Magnetizing process and trapped field of
REBaCuO and MgB2 superconducting bulks”□ICEC24-ICMC2012 (Fukuoka) (5.1418)“Trapped field and temperature rise in
MgB2 bulks magnetized by pulsed
field”☆ISS2013 (Tokyo) (11.19)“Trapped field and flux dynamics in
MgB2 superconducting bulks
magnetized by pulsed field”☆IU-MRS (Fukuoka) (8.28-31)“Characteristics and trapped field of
REBaCuO and MgB2 superconducting
bulks”★PASREG2015 (Liege, Belgium) (9.1-5)“Pulsed field magnetization for (RE)BCO andMgB2 superconducting bulks and theirapplications”□MT25 (Seoul, South Korea) (10.18-22)“Trapped field homogeneity in NMR
superconducting bulk magnet by the insertion ofhigh-Jc HTS cylinder with various positions,lengths and shapes”
2016 (H28)☆ASC2016 (Denver, USA) (9.4-11)“Trapped Field Enhancement of a Thin, High-Jc
MgB2 Bulk without Flux Jumps using Pulsed
Field Magnetization with a Split-type Coil with aSoft Iron Yoke”

2017 (H29)□MT25 (Amsterdam, The Netherland) (8.26-9.2)“New proposal of mechanical reinforcement
structures to annular REBaCuO bulk magnet forcompact and cryogen-free NMR spectrometer”★PASREG2017 (Tokyo) (12.11-12)“Mechanical Reinforcement of
REBaCuO Bulk during Field-Cooled
Magnetization -- Road to Achieve
Trapped Field Higher than 20 Tesla –"2018 (H30)★Cambridge ⼤での招待講演(4.11-13)“Recent research progresses in Iwate”★ISS2018 (Tsukuba) (12.12-14)“Mechanical reinforcement of
REBaCuO bulk during field-cooledmagnetization to achieve higher trappedfield without fracture”☆ASC2018 (Seattle, USA) (10.28-11.2)“Influence of Inner Diameter and Height of Ringshaped REBaCuO Bulks on Trapped Field andMechanical Stress during Field-cooled
Magnetization”
42－ 40 －

2019 (R1)2020 (R2)2021 (R3)★PASREG2019 (Prague, Czech) (8.27-30)“A new mechanical reinforcement structure for
REBaCuO bulks during field-cooledmagnetization to achieve higher trapped fields
without fracture”★EUCAS2019 (Glasgow, England) (9.1-5)“A Hybrid Trapped Field Magnet Lens
(HTFML): concept and realization”★PASREG (Shanghai, China: WEB) (11.11-13)“A Hybrid Trapped Field Magnet Lens
(HTFML): concept and validation”

出席した国際会議の開催地
43－ 41 －★ISS2019 (Kyoto) (12.3-5)“A Hybrid Trapped Field Magnet Lens
(HTFML): concept and experimental
realization”

出席した国際会議の開催地－ 42 －

44

１１．外部資⾦獲得『科学研究費補助⾦』（代表のみ）(1) 基盤研究（C）：「ＣＭＲ効果を⽰す Co 系酸化物の磁気相転移とフォノン伝達」、（280 万円）、平成
14〜15 年度
(2) 基盤研究（C）：「超強⼒な超伝導バルク磁⽯の実現と磁束ダイナミックスの解明」、（350 万円）平成 17〜18 年度(3) 基盤研究（C）：「新しいパルス着磁法による７テスラを越える超伝導バルク磁⽯の実現と磁束運動の解明」、（350 万円）平成 19〜20 年度(4) 基盤研究（C）：「スプリット型コイルによる超強⼒な超伝導バルク磁⽯の実現と磁気分離への応⽤」、(420 万円) 平成 23〜25 年度(5) 基盤研究（C）：「MgB2 超電導バルク磁⽯の熱的安定化と強磁場捕捉を実現するパルス着磁技術の開発」、(380 万円) 平成 27〜29 年度（藤代）(6) 基盤研究（C）：「着磁磁場よりも⼤きな磁場を持続的に発⽣できる新規の超電導バルク磁⽯レンズ」、(330 万円) 令和元〜令和 3 年度年度
『奨励⾦』
（代表のみ）(1) 池⾕科学技術振興財団研究助成：「酸化物超伝導体を⽤いた低温領域における熱電冷却素⼦に関する研究」（150 万円）、平成 5 年度
(2) 池⾕科学技術振興財団研究助成：「第１５回低温技術に関する国際会議 (ICEC-15) ジェノバ
(Genova)、イタリア (Italy) 旅費」（35 万円）(3) 平成６年度実吉奨学会研究奨励⾦：「Mn 系酸化物における⾦属・絶縁体転移近傍での電荷整列と熱伝導特性」（60 万円）、平成 9 年度
(4) 東京電⼒（株）研究振興財団海外渡航旅費：「9th International Conference on Modern Material &Technologies (CIMTEC '98)（第９回先端材料および技術に関する国際会議）イタリア・フロレンス」（30 万円）、平成 10 年度(5) ⽇本原⼦⼒研究所先端基礎研究センター黎明研究：「ペロブスカイト鉄族系酸化物のフォノン伝導と格⼦異常」（200 万円）、平成 11 年度(6) 岩⼿⼤学⼤学活性化経費（外部資⾦を導⼊するための経費・展開的な研究）：「Co 系酸化物熱電エ
ネルギー変換材料の開発」（70 万円）、平成 14 年度(7) 岩⼿⼤学学⻑裁量経費（萌芽的教育研究⽀援費）：「低環境負荷型エネルギー変換材料の探索とデバ
イス開発」（35 万円）、平成 17 年度(8) 夢県⼟いわて戦略的研究推進事業：「バルク超伝導体の新しいパルス着磁法の開発と捕捉磁場向上に関する研究」（代表）（1050 万円）
、平成 16〜18 年度(9) 岩⼿⼤学学⻑裁量経費「教員個⼈の研究業績に基づく研究費の配分」（100 万円）、平成 18〜19 年度(10) JST 地域イノベーション創出総合⽀援事業 重点地域研究開発プログラム 平成 20 年度「シーズ発掘試験」、「マイクロモーゼ効果を⽤いた有機半導体薄膜の微細結晶配向制御」（200 万円）(11) 岩⼿⼤学学⻑裁量経費（萌芽的教育研究⽀援費）：「ソフトパスエンジニアリングに関する連続講演会の開催」（45 万円）、平成 20 年度(12) JST 地域イノベーション創出総合⽀援事業 重点地域研究開発プログラム 平成 21 年度「シーズ発掘試験」、「マルチ超伝導バルク磁⽯を⽤いた⾼精度磁気分離技術の開発」（200 万円）(13) 平成 23 年度 JST 研究成果展開事業 研究成果最適展開⽀援プログラムフィージビリティスタディ
【ＦＳ】ステージ 探索タイプ「超電導バルク磁⽯を⽤いた放射能汚染⼟壌や⽔の除染⽤吸着剤の開発」(300 万円)(14) 平成 24 年度 JST 復興促進プログラム(A-STEP)探索タイプ「モーゼ効果を⽤いた熱電変換⽤ポリマ
ー薄膜の⾼性能化と特性向上」(300 万円)
45－ 43 －

(15) ⽇本学術振興会「⼆国間交流事業」、（英国との交流事業）「超電導モーター応⽤を⽬指した超電導バルク材の作製及び着磁・要素技術の開発」、平成 26 年〜28 年 (442.5 万円)(16) JST A-STEP 機能検証フェーズ、「着磁磁場より強い磁場を持続的に発⽣できるハイブリッド型超電導バルク磁⽯レンズの開発」(2018-2019) (300 万円)(17) JST A-STEP トライアウト、「勾配磁場により微⼩重⼒環境を実現する新しい超電導バルク磁⽯装置の開発」(2020-2022) (300 万円)

46－ 44 －

科研費、競争的外部資⾦の獲得状況

47－ 45 －

１２．研究室の卒業論⽂、修⼠論⽂、博⼠論⽂の題⽬(平成 3 年度, 1991 年度：池部研究室)
卒業論⽂
B1.⼯藤優⼀「噴霧熱分解法による酸化物超伝導体超微粒⼦の作製」
B2.廻⾕和志「Bi 系超伝導体における Pb 添加と超伝導特性の関係」
B3.諸井 睦「熱電対を⽤いた Bi 系超伝導体の熱伝導率測定」
B4.⿑藤道明「YBa2Cu3O7-d単結晶の作製」
B5.堀切祐仁「Y 系超伝導体の粒径と超伝導特性の関係」(平成 4 年度,1992 年度：池部研究室)
卒業論⽂
B6.⽇下和彦「Bi 系酸化物超伝導体厚膜に関する研究」
B7.栗原 崇「低熱侵⼊型酸化物超伝導体/合⾦シーステープに関する研究」
B8.幸野泰史「酸化物超伝導体のゼーベック係数、熱伝導率に関する研究」
B9.内藤智之「酸化物超伝導体の熱拡散率に関する研究」
B10 佐⽵隆志「ひずみゲージによる熱膨張測定に関する研究」
B11.菅尾克弘「差動変圧器を⽤いた熱膨張計の試作」
B12.中島正晶「低温で動作する熱電冷却素⼦に関する研究」(平成 5 年度, 1993 年度：池部研究室)
修⼠学位論⽂M1.⼯藤優⼀「酸化物超伝導体粒⼦の作製と線材化に関する研究」
卒業論⽂
B13.岩⽥邦男「酸化物超伝導体の熱起電⼒に関する研究」
B14.楠⾒武⽣「A/D コンバータを⽤いた熱拡散率測定システムの開発」
B15.⽣井正夫「酸化物超伝導体の熱電冷却への応⽤に関する研究」
B16.及川滋暁「Ag ドープ Bi2212 結晶の異⽅性輸送特性に関する研究」
B17.中川貴⼦「Y 系酸化物超伝導体の熱拡散率に関する研究」
B18.関 修章「Bi 系酸化物超伝導体の線材化に関する研究」
B19.⼋⽊真如「Bi(2201)系酸化物超伝導体試料の作製」(平成 6 年度, 1994 年度：池部研究室)
修⼠学位論⽂M2.内藤智之「酸化物超伝導体の熱拡散率、熱伝導率に関する研究」
M3.⽇下和彦「酸化物超伝導体を⽤いた低温で動作する熱電冷却素⼦に関する研究」
卒業論⽂
B20.久保澤 誠「Ag+YBa2Cu3O7 系のパーコレーション伝導に関する研究」
B21.岩 慎⼀「Nd2-xCexCuO4 の Ce 濃度と熱伝導率」
B22.⽥鎖賢⼆「Bi2Sr2CaCu2Ox 酸化物超伝導体の超伝導特性に関する研究」
B23.中⾥規実⽣「酸化物超伝導体の熱拡散率と⽐熱に関する研究」
B24.野沢孝紀「RBa2Cu3O7-d (R:希⼟類元素）の超伝導特性に関する研究」
B25.橋⼭淳⼀「Y-Ni-B-C 及び Y-Pd-B-C の⾦属超伝導体に関する研究」
B26.福井達明「YBa2Cu3O7-dの Zn 置換と超伝導特性に関する研究」
B27.吉⽥昌浩「酸化物超伝導体を⽤いた熱電冷却素⼦に関する研究」
48－ 46 －

(平成 7 年度, 1995 年度：池部研究室)
修⼠学位論⽂M4.⼋⽊真如「Nd2-xCexCuO4-dにおける熱輸送特性と超伝導」
卒業論⽂
B28.浜⽥和宏「GaAs 単結晶の熱伝導率と散乱機構」
B29.⾼橋重雄「YBa2Cu3O7-dの Y サイト置換効果と熱伝導率」
B30.芝崎有三「La2-xBaxCuO4 系超伝導体の熱的、電気的輸送特性」
B31.冨⽥ 健「酸化物超伝導体の熱伝導率に関する理論解析」
B32.昆野吉幸「極低温(10 K 以下）における熱伝導率測定法の開発」
B33.湊 洋⼀「Ag+YBCO 系のパーコレーション伝導とモデル解析」(平成 8 年度, 1996 年度：池部研究室)
修⼠学位論⽂M5.中⾥規実⽣「酸化物超伝導体の熱伝導率及び熱拡散率に関する研究」
M6.⼩⼭道夫「MBE を⽤いた銅及び遷移⾦属酸化膜薄膜の作製」
卒業論⽂
B34.松枝 ⻫「酸化物超伝導体における接触電気抵抗と臨界電流に関する研究」
B35.杉村茂昭「室温以上の熱伝導率測定装置の開発と評価に関する研究」
B36.菅原⾄朗「V2O3 における⾦属・絶縁体転移と熱伝導率に関する研究」
B37.三上達也「３点法による熱拡散率測定と接触熱抵抗に関する研究」
B38.菊池 勉「MBE 法による銅およびマンガン酸化薄膜の作製及び評価に関する研究」
B39.松尾昌宏「T*構造を有する 214 系酸化物超伝導体の作製と熱伝導率に関する研究」(平成 9 年度, 1997 年度：池部研究室)
修⼠学位論⽂M7.芝崎有三「(214)系超伝導体における熱輸送特性」
M8.湊 洋⼀「室温以上の温度領域における熱拡散率、熱伝導率測定法の開発」
M9.昆野吉幸「La1-xSrxMnO3 の磁気相転移と熱輸送」
卒業論⽂
B40.王⼦⽥修⼀「FZ 法で作製した La1-xSrxMnO3 結晶の熱伝導率と熱拡散率」
B41.岡本⿓也「Nd2-xCexCuO4-d超伝導体の Cu サイト置換効果」
B42.⽚桐洋⼀「Ag+YBCO 複合材料の熱起電⼒から⾒たパーコレーション」
B43.河⻄ 孝「La1-xCaxMnO3 結晶の磁気相転移と熱伝導率」
B44.根城智哲「FZ 法で作製した Nd0.5Sr0.5MnO3 結晶における電荷整列相転移と熱伝導」
B45.⼊江 剛「酸化物超伝導体ー銅ブロック間の接触熱抵抗」(平成 10 年度, 1998 年度：池部研究室)
修⼠学位論⽂M10.三上達也「La1-xSrxMnO3 (0.48＜x＜0.82)の電荷整列現象とフォノン散乱機構」
M11.菅原⾄朗「R1-xSrxMnO3 (R=Nd, Pr, Sm, Gd)の相転移と熱伝達特性」
M12.菊池 勉「La1-xCaxMnO3 の磁気相転移と熱輸送特性」
卒業論⽂
B46.⼩澤英⾏「Mn 酸化物 R1-xSrxMnO3 における R サイトのイオン半径と相転移」
B47.加納伸吾「La1-xCaxMnO3 の磁場中熱伝導率、熱拡散率測定」
B48.川村広貴「Nd2-xCexCuO4-d超伝導体の Cu サイト置換効果」
B49.⽊沢健公「滴定法による Mn 酸化物中の Mn イオン価数の定量について」
B50.島 健悟「Na(MxCo1-x)2O4 (M=Fe, Ni, Mn, Cu)の熱電効果」
B51.野 明彦「異⽅性物質に対する新しい異⽅的熱伝導率決定法の提案」
49－ 47 －

B52.藤原直将「Pr1-xCaxMnO3 (0＜x＜1)の作製と熱伝達特性」(平成 11 年度, 1999 年度：池部研究室)
修⼠学位論⽂M13.王⼦⽥修⼀「RE1-xAExMnO3 (x〜0.9)のキャント磁性と輸送特性」
M14.岡本⿓也「異⽅性物質に対する異⽅的熱伝導率の同時決定法」
卒業論⽂
B53.菅原昭洋「(La1-zNdz)1-xSrxMnO3 の x=0.5 近傍における磁気・電荷秩序」
B54.⾼橋拓也「RuSr2GdCu2O8 の超電導性と強磁性」
B55.滝⼝ 勝「FZ 法で作製した La1-xSrxMnO3 (x〜0.5)の磁化特性」
B56.照井明彦「La1-xBaxMnO3 の輸送特性と相図の決定」
B57.平松美穂「ヨウ素滴定法を⽤いた Mn 酸化物における酸素量の定量」
B58.⼭崎 哉「Pr0.65Ca0.35MnO3 における Mn サイトの遷移⾦属置換効果」(平成 12 年度, 2000 年度：池部研究室)
修⼠学位論⽂M15.⼩澤英⾏「R1-xAxMnO3 (R=La, Pr, Nd : A=Ca, Sr, Pb)における格⼦歪みと相転移」
M16.加納伸吾「La1-xBaxMnO3, Pr1-xCaxMnO3 の磁場中輸送特性」
M17.沼野 誠「La1-xCaxMnO3+dの相転移に及ぼす酸素含有量の影響」
卒業論⽂
B59.⼩林⼤悟「La1-xPbxMnO3+dの輸送特性と相図の決定」
B60.中家広顕「パイロクロア型酸化物 R2Mo2O7 (R=Nd, Sm, Gd)の作製に関する研究」
B61.柏⽥陽平「La0.65Ca0.35MnO3+dの低抵抗化に関する研究」
B62.⼤久保和紘「RuSr2GdCu2O8 の超電導特性について」
B63.佐藤⼀晶「FZ 法による La1-xCaxMnO3+d単結晶の育成と評価」
B64.清⽔輝幸「La1-xCaxMnO3 の作製条件による電気抵抗率の変化について」(平成 13 年度, 2001 年度：池部研究室)
修⼠学位論⽂M18.⾼橋拓也「RuSr2GdCu2O8 (Ru1212)の超電導特性向上に関する研究」
M19.滝⼝ 勝「FZ 法による La1-xCaxMnO3 の単結晶成⻑と評価」
M20.⼭崎 哉「Pr1-xCaxMnO3 系における Mn サイトへの遷移⾦属置換効果」
卒業論⽂
B65.伊藤健⼀「CaMnO3+dの酸素含有量と諸物性について」
B66.⼩滝茂則「超電導体 MgB2 の作製と評価」
B67.鈴⽊和義「La0.8Sr0.2(Mn1-zCoz)O3 の磁性と伝導」
B68.⻄ 利勝「CMR 効果を⽰す La1-xSrxCoO3 の作製と電気的、磁気的性質」
B69.村上 強「La1-xCaxMnO3 の単結晶育成に関する研究」(平成 14 年度, 2002 年度：池部研究室)
修⼠学位論⽂M21.柏⽥陽平「La1-xAExCoO3+d (AE=Sr, Ba, Ca)の磁性と熱輸送特性」
卒業論⽂
B70.寺沢耕太郎「FZ 法による La2-xSrxNiO4+d単結晶の作製に関する研究」
B71.澤⽥健⼆「La1-xSrxCoO3 の作製と物性評価」
B72.三⽥泰久「Ca1-xSrxMn3-dの磁性と伝導に関する研究」
B73.内藤博史「FZ 法による La1-xSrxCoO3+dの単結晶作製に関する研究」
B74.伊藤俊彦「RuSr2GdCu2O8-dの超電導特性向上に関する研究」
50－ 48 －

B75.佐々⽊ 学「La2-xSrxNiO4+d焼結体作製と物性評価」(平成 15 年度, 2003 年度：池部研究室)
修⼠学位論⽂M22.熊⾕達也「Pr0.65Ca0.35MnO3 における Mn サイトの置換効果」
M23.鈴⽊和義「FZ 法における La2-XSrXNiO4 の結晶成⻑と物性評価」
卒業論⽂
B76.伊藤真治「LaCoO3 系酸化物における酸素量の決定」
B77.植⽥祐史「バルク超伝導体のパルス着磁における温度上昇」
B78.篠原 聡「La2-xSrxNiO4+dの FZ 成⻑と性能評価」
B79.鈴⽊ 雄「RE1-xCaxMnO3 系の熱電特性に及ぼすＡサイトのイオン半径の影響」
B80.藤原 篤「Pr0.65Ca0.35MnO3 における Mn サイトへの置換効果」(平成 16 年度, 2004 年度：池部研究室)
修⼠学位論⽂
M24.⾦⼭雅彦「バルク超伝導体のパルス着磁における捕捉磁場と発熱解析」
M25.内藤博史「La1-XCaXCoO3-dの酸素⽋損量の低減と物性評価」
卒業論⽂
B81.⾚間和也「DyBaCuO 系超伝導バルクの結晶成⻑と超伝導性」
B82.川⼝秀介「バルク超伝導体のパルス着磁における発熱現象と温度シミュレーション」
B83.久保⽥ 徹「SrPbO3 系 n 型熱電変換材料の作製と性能評価」
B84.姿 拓幸「RECoO3 (RE:希⼟類元素)の熱伝導率と熱膨張率」
B85.武⽥紘幸「CaMnO3 の Mn サイト置換と熱伝導率」
B86.⽴岩達也「Gd 系バルク超伝導体を⽤いた４テスラを超える捕捉磁場の実現」
B87.⻑坂佑⼀「Pr1-XCaXMnO3 における Mn サイトの Ru 置換効果」
B88.箱⽯真⼸「(La1-ZYZ)0.5Ca0.5CoO3 の熱電変換特性」(平成 17 年度, 2005 年度)
修⼠学位論⽂M26.藤原 篤「パルス着磁による新しい超電導バルク磁⽯の開発」
M27.鈴⽊ 雄「La1-XAEXCoO3 (AE=Ca, Sr, Ba)の熱電特性」
卒業論⽂
B89.菊池健太郎「n 型熱電材料 RE1-XCeXCoO3 実現の可能性について」
B90.佐久⼭誉⽣「211 相を含まない DyBaCuO 系超伝導バルクの結晶成⻑」
B91.佐塚悠介「４⾓形超伝導バルクのパルス着磁特性」
B92.李沢未央「RE1-XCaXCoO3 のトレランス因⼦と物性評価」
B93.⾼橋則史「DyBaCuO 系超伝導バルクの結晶成⻑と超伝導性--2005」
B94.⽇⼭拓也「MMPSC 法による超伝導バルクのパルス着磁特性」
B95.⼋重樫晃⼀「FZ 法による RECoO3 系材料の作製と物性評価」(平成 18 年度, 2006 年度)
修⼠学位論⽂M28.⽴岩達也「MMPSC 法による超伝導バルクのパルス着磁現象と磁束運動」
卒業論⽂
B96.⽥澤淳⼀「DyBaCuO 系超伝導バルクの作製と評価 2006」
B97.岡村宏紀「磁気分離⽤５連型超伝導バルク磁⽯装置の作製と特性評価」
B98.⽋端浩介「65mm ⼤型超伝導バルクのパルス着磁特性」 概要
B99.今野友貴「Co 系酸化物 REBaCo2O5-dの酸素量決定と物性評価」
51－ 49 －

B100.佐藤清知「含浸成⻑法による DyBaCuO 系超伝導バルクの作製と超伝導特性」
B101 野村幸靖「ErBaCuO 超伝導バルクの結晶成⻑と熱伝導率」
B102.松⽥寛之「REBaCo2O5-dの結晶構造と A サイトイオン半径との関係」(平成 19 年度, 2007 年度)
博⼠学位論⽂D1.藤根陽介「ペロブスカイト型 Co 系酸化物の熱電特性に関する研究」
修⼠学位論⽂
M29.⽯⽥未央「Pr イオンを含む RE1-XCaXCoO3 系の⾦属絶縁対転移と格⼦異常」
M30.⽇⼭拓也「パルス磁場印加における超伝導バルク中の磁束の運動と捕捉特性」
卒業論⽂
B103.⼩林⼤地「バルク超伝導体のパルス着磁における発熱現象のシミュレーション」
B104.佐々⽊寛⼦「Pr1-XCaXCoO3 系酸化物の⾦属絶縁体転移と格⼦異常」
B105.佐々⽊陽光「ZnO 系及び CuO 系熱電変換材料の創成と特性評価」
B106.三浦 崇「強いピン⽌め⼒を有する超伝導バルクに対するパルス着磁特性」
B107.三上真詩⼦「Ce 置換した La2-XSrXCuO4 の超伝導特性」
B108.⼭⼝⼤吾「Pr 置換した YBCO 系超伝導バルクの作製と超伝導特性」(平成 20 年度, 2008 年度)
修⼠学位論⽂M31.⼋重樫晃⼀「超伝導バルク磁⽯を⽤いた局所磁場変調に関する基礎的研究」
M32.今野友貴「La2-x-ySrxCeyCuO4 超伝導体の単結晶成⻑と Ce 置換効果」
M33.佐藤清知「YBaCuO バルク超伝導体における Y サイトの La, Pr 置換効果」
M34.⽋端浩介「超伝導バルクのパルス着磁における磁束捕捉特性の向上に関する研究」
卒業論⽂
B109.上野康正「RE2CuO4 (RE:希⼟類元素)の作製と熱伝導率に関する研究」
B110.⼤畑量⼦「La2-xSrxCuO4 超伝導体の La サイトの Ce 置換効果に関する研究」
B111.加藤元晴「Pr1-XCaXCoO3 系酸化物の熱電変換特性に関する研究」
B112.菊池康晃「YBaCuO バルク超伝導体の結晶成⻑と Y211 粒⼦の微細化に関する研究」
B113.平井尚⼦「La2-XSrXCoO4 系酸化物の作製と物性評価に関する研究」
B114.古澤 允「バルク超伝導体の着磁⽅法の違いによる捕捉磁場特性に関する研究」
B115.古⽥⼤樹「パルス着磁における超伝導バルク内部の温度測定に関する研究」(平成 21 年度, 2009 年度)
修⼠学位論⽂M35.佐々⽊寛⼦「Pr1-xCaxCoO3 系の⾦属絶縁体転移とスピン状態転移の共存」
M36.三浦 崇「パルス磁場印加における超伝導バルク内部の磁束運動と捕捉磁場分布」
M37.⼭⼝⼤吾「RE2CuO4（RE：希⼟類⾦属）単結晶の育成と熱伝導特性」
M38.松⽥寛之「LaCoO3 系酸化物のスピン転移とフォノン散乱」
卒業論⽂
B116.荒屋敷貴⼤「スライスした超伝導バルクのパルス着磁特性と厚さ⽅向の捕捉磁場分布」
B117.⼩川 悟「(Pr1-yYy)1-xCaxCoO3 系の⾦属絶縁体・スピン状態転移」
B118.⼩⼭ 允「2 段に重ねた超伝導バルクのパルス着磁特性」
B119.袖平智樹「La2-xAExCoO4 (AE=Ba, Ca)の作製と物性評価」
B120.⾼橋 良「La214 系超伝導体の La サイトの Ce, Tb 置換効果」
B121.半⽥拓也「マグネトスキャン法による臨界電流密度分布測定について」52－ 50 －

(平成 22 年度, 2010 年度)
修⼠学位論⽂
M39.上野康正「La2-xSrxCuO4 系超伝導体単結晶の育成と渦⽷系相転移」
M40.加藤元晴「An+1ConO3n+1 系酸化物（n=1, 2, ∞）の次元性と熱電変換特性」
M41.菊池康晃「DyBaCuO 系超電導バルクの作製と Dy サイトの元素置換効果」
M42.古⽥⼤樹「超電導バルクのパルス着磁特性と臨界電流密度分布の相関」
卒業論⽂
B122.楳原久美⼦「RE1-xCaxCoO3 (x>0.5)の単相合成に関する研究」
B123.佐々⽊智久「⼤型 MgB2 超電導体バルクの作製と捕捉磁場特性」
B124.関⼝哉太「CaTiO3 系熱電変換材料の作製と物性評価」
B125.⽟⽥裕⼠「異なる Jc 分布を有する超電導バルクのパルス着磁特性」
B126.古森健太「Pr イオンを含まない RE0.7Ca0.3CoO3 系における⾦属絶縁体転移現象の探索」
B127.吉⽥直樹「熱電変換材料 RE1-xSrxCoO3 (X=0.5, 0.75)の作製と物性評価」(平成 23 年度, 2011 年度)
修⼠学位論⽂M43.荒屋敷貴⼤「超電導バルクの着磁における臨界電流密度の不均⼀が及ぼす磁束運動と捕捉磁場」
M44.⼩川 悟「Pr-Ca-Co-O 系酸化物の⾦属絶縁体転移における Pr イオンの価数シフト」
M45.⾼橋 良「(Sm2-xREx)CuO4 (RE=La, Nd)単結晶の熱伝導率におけるマグノンピーク」
卒業論⽂
B128.⽒家 徹「酸化物超伝導体 Bi2201 単結晶の育成と超伝導特性」
B129.武⽥⼤輝「マグネトロンスパッタ法による Pr-Ca-Co-O 系薄膜の作製と物性評価」
B130.⽥村拓也「四⾓形状を有する超電導バルクの着磁特性」
B131.寺本惇⼀「有機半導体薄膜熱電材料の作製と熱電特性評価」
B132.松⽥英司「In2-xGexO3 の熱電特性」
B133.渡辺卓真「RE(Co1-yMy)O3 ((RE=Gd, Sm, M=Ni, Fe)の熱電特性」(平成 24 年度, 2012 年度)
修⼠学位論⽂
M46.⼩⼭ 允「超電導バルクのパルス着磁における磁束運動・温度変化シミュレーション」
M47.佐々⽊智久「⼤型 MgB2 超電導バルクの実現と強磁場捕捉特性に関する研究」
M48.関⼝哉太「n 型 ZnO 系熱電変換材料の Zn サイト置換効果と熱電特性向上に関する研究」
M49.古森健太「n 型 In2O3 系及び CaMnO3 系熱電材料の⾼密度化と熱電特性向上に関する研究」
M50.吉⽥直樹「Cu1-xLixO 系熱電変換材料の⾼性能化に関する研究」
M51.半⽥拓也「Generic seed を⽤いた超電導バルクの結晶成⻑」
卒業論⽂
B134.阿部凛太郎「n 型 RECoO3 系熱電材料の探索に関する研究」
B135.佐藤史⼦「熱電モジュールの発電性能と耐久性に関する研究」
B136.細川潤基「FCM 法による GdBCO 系超電導バルクの捕捉磁場特性」
B137.吉⽥卓史「⼤型 MgB2 バルクの作製と捕捉磁場特性に関する研究」 ０(平成 25 年度, 2013 年度)
修⼠学位論⽂M52.⽒家 徹「MgB2 超電導バルクのパルス着磁特性に関する研究」
M53.武⽥⼤輝「(Pr,RE)-Ca-Co-O 系酸化物における(Pr,RE)イオンの価数シフトに関する研究」
M54.⽥村拓也「REBaCuO 系超電導バルクのパルス着磁シミュレーションに関する研究」
M55.渡辺卓真「不定⽐酸化物 TiOx の作製と熱電特性に関する研究」
53－ 51 －

卒業論⽂
B138.⼤井絵⾥⼦「ストレインゲージ法を⽤いた超電導線材の熱収縮測定に関する研究」
B139.⽯⼾⾕ 和「REBaCuO 系超電導バルクの磁場中冷却着磁に関する研究」
B140.貫洞翔太「FZ 法による Bi2223 系超伝導体の単結晶育成に関する研究」
B141.佐々⽊みなみ「MgB2 超電導バルクの捕捉磁場特性に対する不純物置換効果」
B142.⾼橋祥平「CoSb3 系スクッテルダイト化合物の作製と熱電特性に関する研究」
B143.野⽥裕介「Pr-Ca-Co-O 系酸化物の Pr サイト置換効果に関する研究」
B144.⽔野 州「AxCoO2 系酸化物(A=Li, Na, K)の合成と熱電変換特性」
B145.望⽉豪彦「⾼性能 MgB2 超電導バルクのパルス着磁特性に関する研究」
B146.遠藤友理「SPS 法による MgB2 バルクの作製と捕捉磁場特性に関する研究」(平成 26 年度, 2014 年度)
修⼠学位論⽂M56.阿部凜太郎「In2O3-SnO2 系熱電変換材料の⾼性能化に関する研究」
M57.吉⽥卓史「Ti 添加 MgB2 超電導バルク磁⽯の⾼性能化」
卒業論⽂
B147.Amirah Binti Che Amat "Characteristics of MgB2 superconducting bulks fabricated by spark plasma
sintering"
B148.稲垣絵梨⼦「パルスレーザ蒸着法を⽤いた REBCO 系薄膜(RE=Nd, Sm)の作製と評価」
B149.荻野 新「Infiltration 法を⽤いた MgB2 超電導バルクの作製と超電導特性」
B150.佐々⽊⼀真「Nb-doped SrTiO3 の作製と熱電特性の評価」
B151.相⾺史弥「円柱状超電導バルクにおけるパルス着磁と磁束侵⼊挙動に関する研究」
B152.原 貴充「ミスフィット型 Ca3Co4O9 系化合物の作製と熱電変換特性の向上」
B153.⾼杉 弥「TSMG 法による YBaCuO 超電導バルクの作製と評価」(平成 27 年度, 2015 年度)
修⼠学位論⽂M58.遠藤友理「スパークプラズマ焼結法で作製した MgB2 超電導バルクの捕捉磁場特性」
M59.野⽥裕介「パルスレーザ蒸着法より作製した(Pr1-yYy)1-xCaxCoO3 単結晶薄膜の作製と⾦属絶縁体転移」
M60.⽔野 州「BiCuSeO 系材料の熱電変換特性に及ぼすキャリアドープとボールミル効果」
M61.望⽉豪彦「MgB2 及び REBaCuO 超電導バルクのパルス着磁特性とシミュレーション解析」
卒業論⽂
B154.阿久澤慶太「MgB2 超電導体へのカーボンドープ効果」
B155.⽯澤 衛「Sr 置換した BiCuSeO 系材料の熱電変換特性とボールミル効果」
B156.⾼橋圭太「ソレノイド型とスプリット型コイルを⽤いた超電導バルクのパルス着磁とシミュレーション」
B157.⾼橋裕平「MgB2 超電導体の Mg サイトへのチタン族元素置換効果」
B158.⾼橋勇⽮「GdBaCuO 超電導バルクの結晶成⻑と捕捉磁場特性」
B159.滝村 武「SnSe 系熱電変換材料における Sn サイトへの Cu 置換効果」
B160.照井 茜「MOD 法による RENiO3 系薄膜の作製と⾦属絶縁体転移」
B161.仲保雄平「MOD 法による RECoO3 系薄膜の作製と物性評価」(平成 28 年度, 2016 年度)
修⼠学位論⽂M62.稲垣絵梨⼦「バッファー層及び薄膜種結晶を⽤いた YBaCuO 超電導バルクの結晶成⻑」
M63.荻野 新「Infiltration Growth 法による MgB2 バルクの作製と浸透現象」
M64.佐々⽊⼀真「⾼温における熱電変換薄膜評価装置の構築と信頼性の評価」
54－ 52 －

M65.原 貴充「SnSe エピタキシャル薄膜作製の最適化と特性評価」
卒業論⽂
B162.⾚⽯和典「(Y, Dy)BaCuO 超電導バルクの育成と捕捉磁場特性」
B163.叶 千学「Pr1-xSrxFeO3 の作製と熱電変換特性評価」
B164.熊⾕ 毬「MgB2 バルクの捕捉磁場特性に対する Ge 添加効果」
B165.笹原隆太「SnSe の熱電特性に及ぼすボールミル効果」
B166.下屋敷郁陽「波形制御されたパルス磁場を印加した超電導バルクの捕捉磁場特性に関する研究」
B167.富樫遥太「⾮晶質ボロンを⽤いた浸透法による MgB2 の作製と臨界電流特性」
B168.安⾥祐輝「BiCuSeO 化合物中の Se ⽋損が熱電変換特性に及ぼす影響」(平成 29 年度, 2017 年度)
修⼠学位論⽂M66.阿久澤慶太「(Pr,Ca)CoO3 系試料の Co サイト置換や酸素⽋損が⾦属絶縁体・スピン状態転移へ及ぼす影響」
M67.⽯澤 衛「PLD 法で作製した Bi1-xSrxCuSeO 系単結晶薄膜の結晶配向及び結晶性と熱電特性評
価」
M68.⾼橋圭太「超電導バルクの着磁現象とその応⽤に関する研究」
M69.⾼橋裕平「⾼充填率 MgB2 超電導バルクの作製と磁束ピン⽌め特性」
M70.⾼橋勇⽮「複数の希⼟類元素を含む⾼温超電導バルク結晶の成⻑と超電導特性」
卒業論⽂
B169.佐々⽊駿⼀「BiCu(Te, Se)O の作製と熱電特性」
B170.澤⽥渓⼈「(Y, Gd)-Ba-Cu-O 超電導バルクの結晶成⻑と超電導特性」
B171.当摩悠希「SPS 法で作製した MgB2 超電導バルクの捕捉磁場特性と粒間結合性の相関」
B172.永⼭正彦「Bi2Te3-xSbx 熱電材料の SPS 法による作製の最適化と熱電特性」
B173.難波 空「超電導バルクの磁場中冷却着磁における電磁界・温度・応⼒の連成解析」
B174.平野達也「スプリットコイルを⽤いた超電導バルクのパルス着磁特性」(平成 30 年度, 2018 年度)
修⼠学位論⽂M71.叶 千学「RE1-xSrxFeO3 (RE:希⼟類元素)における⾦属-絶縁体転移」
M72.笹原隆太「p 型及び n 型 BiSb 系材料の熱電変換特性に関する研究」
M73.下屋敷郁陽「REBaCuO 系超電導ディスクバルクのパルス着磁における電磁界・温度・応⼒特性」
卒業論⽂
B175.⻘⽊亮汰「歪みゲージを⽤いた様々な材料の低温熱収縮測定」
B176.天瀬洸太「KFe2Se2 バルク体の作製と超伝導特性」
B177.伊藤直広「BiCuSeO の熱電特性に対する Ce 添加効果」
B178.鎌⽥⼤空「TSIG 法で作製した YBaCuO 系超伝導バルクのパルス着磁特性 」
B179.駒本康平「Nb3Sn バルク体の作製と超伝導特性」
B180.近藤茜⾳「PrBaFe2O5 の固体燃料電池電極としての可能性評価」(令和元年度, 2019 年度)
修⼠学位論⽂
M74.佐々⽊駿⼀「BiCuSeO の熱電特性に対する窒素置換効果」
M75.澤⽥渓⼈「FeSe 系超伝導バルク体の作製と超伝導特性」
M76.難波 空「ハイブリッド型超電導バルク磁⽯レンズ(HTFML)の実現と⾼性能化に関する研究」
M77.平野達也「超電導バルクのパルス着磁における磁束ダイナミックスに関する研究」
55－ 53 －

卒業論⽂
B181.千葉誠治「超伝導バルク磁⽯と励磁⽤超伝導電磁⽯との磁気カップリング現象」
B182.及川広希「Ti ドープした MgB2 超伝導バルク体の浸透法による作製と捕捉磁場特性」
B183.⼤久保敬汰「シミュレーションを⽤いた形状の異なる超電導リングバルクのパルス着磁特性」
B184.⼩林⼤地「浸透法による Nb3Sn 超伝導バルク体の作製と捕捉磁場特性 」
B185.新⽥基⼰「ハイブリッド型超電導バルク磁⽯レンズ(HTFML)のパルス着磁シミュレーション」
B186.菅原直⼈「Co 置換した BaFe2As2 超伝導体の作製と超伝導特性」
B187.望⽉悠平「ペロブスカイト型 Fe 系酸化物の作製と輸送特性」
B188.本宮⼤輔「燃焼合成法による BiCuSeO の作製と熱電特性」(令和 2 年度, 2020 年度)
博⼠学位論⽂D2.⾼橋圭太「Realization of superconducting bulk magnets with higher magnetic field gradient to provide aquasi-zero gravity space on earth」
修⼠学位論⽂
M78.天瀬洸汰「Nb3Sn および Nb3Al 超伝導バルク体の作製と着磁特性の研究」
M79.鎌⽥⼤空「超電導バルクのパルス着磁におけるコイル形状とヨークの効果」(令和 3 年度, 2021 年度)
博⼠学位論⽂D3.⾼橋裕平「コンパクト NMR 装置の実現に向けた MgB2 超伝導バルク磁⽯ユニットの開発」
修⼠学位論⽂M80.新⽥基⼰「超電導リングバルクのパルス着磁における熱応⼒破壊の可能性に関する研究」

56－ 54 －

１３．担当した講義
学部

電⼦⼯学 (1994~1996)
物理学概論 (1994~1996)
電磁気学 (1996~2003)
電⼦⼯学概論 (1997)
電⼦材料学 II (1998~2000)
半導体材料学 (2001~2006)
電⼦デバイス⼯学 (2001~2019)電磁気学 II (2004~2019)
微分⽅程式 (2006~2008)
科学技術英語 (2009~2010)
マテリアル⼯学概論 (2010~2015)
ソフトパス理⼯学概論 (2016~2019)

⼤学院

電⼦計測学特論 (1994~1996)
電⼦物性⼯学特論 (1998~2008)
半導体デバイス⼯学特論 (2009~2019)
機器分析学特論 (2011~2015)
電⼦機能材料⼯学特論 (2017~2019)
グローバルキャリアデザイン (2017~2021)

57－ 55 －

１４．略歴

昭和 32 年(1957 年) 3 ⽉ 8 ⽇⽣まれ（岩⼿県東磐井郡千厩町（現:⼀関市千厩町））
昭和 50 年(1975 年) 3 ⽉ 岩⼿県⽴⿊沢尻北⾼等学校
卒業
昭和 55 年(1980 年) 3 ⽉ 東北⼤学⼯学部電⼦⼯学科卒業
昭和 55 年(1980 年) 4 ⽉ 東北⼤学⼤学院⼯学研究科博⼠前期課程電⼦⼯学専攻 ⼊学
昭和 57 年(1982 年) 3 ⽉
同上修了
昭和 57 年(1982 年) 4 ⽉ 東北⼤学⼤学院⼯学研究科博⼠後期課程電⼦⼯学専攻 ⼊学
昭和 60 年(1985 年) 3 ⽉
同上
修了
⼯学博⼠
博⼠学位論⽂題⽬：「蒸気圧制御下における相図の研究」東北⼤学（⼯第 987 号）
昭和 60 年(1985 年) 4 ⽉(財)半導体研究振興会半導体研究所研究員
平成 元年(1989 年) 5 ⽉
九州⼯業⼤学助⼿（情報⼯学部機械システム⼯学科）
平成 3 年(1991 年) 8 ⽉
岩⼿⼤学助⼿（⼯学部電⼦⼯学科）
平成 4 年(1992 年) 4 ⽉
岩⼿⼤学助⼿（⼯学部材料物性⼯学科）（学科改組による配置換え）
平成 5 年(1993 年)12 ⽉ 岩⼿⼤学助教授（⼯学部材料物性⼯学科）
平成 15 年(2003 年) 7 ⽉
⽂部科学省短期在外研究員（チェコ科学アカデミー物理学研究所、
平成 15 年 9 ⽉まで）
平成 18 年(2006 年) 3 ⽉
岩⼿⼤学教授（⼯学部材料物性⼯学科）
平成 19 年(2007 年) 4 ⽉
岩⼿⼤学⼯学部材料物性⼯学科⻑（平成 20 年 5 ⽉まで）
平成 20 年(2008 年) 6 ⽉
岩⼿⼤学教育研究評議員（平成 24 年 3 ⽉まで）
平成 23 年(2011 年) 4 ⽉
岩⼿⼤学教授（⼯学部マテリアル⼯学科）（学科改組による配置換え）
平成 24 年(2012 年) 4 ⽉
岩⼿⼤学地域連携推進センター⻑（平成 26 年 3 ⽉まで）
平成 26 年(2014 年) 4 ⽉
岩⼿⼤学教育研究評議員（平成 31 年 3 ⽉まで）
平成 28 年(2016 年) 4 ⽉
岩⼿⼤学教授（理⼯学部物理材料理⼯学科マテリアルコース）（学科改組による配置換え）平成 31 年(2019 年) 3 ⽉
岩⼿⼤学教授退職（理事就任のため）
平成 31 年(2019 年) 4 ⽉
岩⼿⼤学理事（研究、復興、地域創⽣担当）
・副学⻑（令和２年３⽉まで）
令和 2 年(2020 年) 4 ⽉
岩⼿⼤学理事（総務、企画、評価、広報担当）・副学⻑（令和４年３⽉まで）令和 4 年(2022 年) 4 ⽉〜 岩⼿⼤学理事（総務、戦略企画担当）
・副学⻑
主要所属学会：低温⼯学会（1992~継続）、応⽤物理学会(1990~2020)、⽇本物理学会(1989~2020)
主要役職：低温⼯学協会 東北・北海道⽀部 ⽀部⻑(2018~2021)
58－ 56 －

１５．研究⽣活の振り返りと謝辞
令和４年３⽉に 65 歳の定年となる年齢に達し、これまでの研究業績を整理し、⾃分⾃⾝の研究⽣活を振り返りたいと考え、この研究業績集を取り纏めた。あくまでも⾃分⾃⾝のための記録である。
私の研究⼈⽣は、1979 年の東北⼤学⼯学部電⼦⼯学科の卒論研究室配属で第３希望の⻄澤潤⼀教授の研究室に配属された時点がスタートである。当初は修⼠課程修了後に企業へ就職する予定であったが、次第に研究の⾯⽩さが分かってきて、博⼠課程への進学という他の同級⽣とは異なる未知の⼈⽣を歩む
ことを決断し、本格的な研究⽣活へ本格的に⼊った。博⼠論⽂のテーマは、前任者の博⼠論⽂内容の再
現・検証と新たな展開であったが、再現性が得られなかった。様々な検討の結果、前任者の博⼠論⽂の主要な結果は装置誤差（エラー）を新規な信号と⾒誤っていたことが博⼠課程３年の春になって明らかになり絶望感に苛まれた。そのため博⼠論⽂の内容は、前任者が⾒誤った原因を明らかにし、⾮常に⼤きなエラーを取り除いた後の⾮常に⼩さな真の信号を⾒積もったことでまとめたが、外部投稿論⽂が１編も無いにも関わらず、博⼠学位論⽂として認めて頂いた。⻄澤教授には学位取得までの６年間と、その後４年間の(財)半導体研究所での研究員⽣活における化合物半導体デバイス開発の産学連携研究では、いろいろと迷惑をお掛けしたが、研究者の⼼構えや研究の本質、産学連携の重要性を学ばせて頂いたことに感謝している。
1989 年からの九州⼯業⼤学助⼿としての２年半は、これまで⾏って来た化合物半導体研究と決別し、酸化物超伝導材料研究に転向した。⻄澤研究室時代では当たり前だった上から研究テーマ・⽅針が与えられる環境から、⼀転して価値ある新しい研究テーマを⾃分で設定し成果を上げることの難しさを経験し、⾃⽴した研究者の在り⽅を苦しみながら模索する時間であった。
1991 年に 30 代前半で学術論⽂が４編しかなく、学科内で多くの反対意⾒があったにもかかわらず、
池部 學先⽣に岩⼿⼤学助⼿として採⽤して頂き、これまでの経験を⽣かして腰を据えて教育研究に邁進しようと⼼に誓った。赴任当初の 30 代中盤から約 15 年間、研究室の全ての研究費を使わせて頂くと同時に、全ての学⽣のテーマ設定から研究指導までを主体的に⾏えたという⾮常に恵まれた経験が、現在まで続く何物にも代えがたい財産となった。さらに、競争的外部資⾦を獲得し研究業績を必ず学術論
⽂や国際会議で発表するという⼤学研究者としての基本姿勢を学ぶことが出来た。改めて池部先⽣には感謝申し上げる。
2006 年に教授に昇進し研究室を主宰することになり、池部研究室の２期⽣である内藤智之君を助⼿に採⽤し、２⼈で教育・研究を推進してきた。研究室の⽅針は「⾃分で試料を作製し、⾃分で評価する」
こととし、超電導体材料と熱電変換材料の研究を推進した。その中で、研究を通しての学⽣の成⻑と、「これは⾯⽩い」と思える研究にいくつか出会い、成果を発表することができた事は⾮常に幸せであった。50 歳位までは主に物理学会に参加し基礎知識や先端研究の状況を学び、⾃分では結晶成⻑や試料作
製・評価と物性関係の「実験だけ」で研究を進めてきたが、物性物理の分野での研究推進に⾃分の知識・能⼒に関する⾏き詰まり感があった。2003 年頃から超電導バルクの着磁研究という応⽤物理学分野の実験を新たに始め、2010 年頃からは着磁シミュレーションを開始した。当初、着磁シミュレーションは実験結果の再現・確認が⽬的だったが、次第にシミュレーションによって実験を予測し、その後に実験で検証するという本来のシミュレーションの利点を発揮できるようになった。その結果として実現したハ
イブリッド型超電導バルク磁⽯の研究や超電導バルクの機械的補強の研究は、まさにシミュレーションと実験の融合で⽣まれた研究成果であり、⾃分の研究スタイルとして”Materials Science and Technology”
は性に合っていたと感じる。2003 年のチェコ科学アカデミー物理学研究所への留学と、その後現在に⾄る Jiri Hejtmanek 博⼠との共同研究（共著論⽂ 13 編）、更に 2013 年の Cambridge ⼤学の Mark Ainslie 博
⼠との国際会議での偶然の出会いから始まった超電導バルクでの共同研究（共著論⽂ 37 編）は、国際共同研究の重要性とグローバルスタンダードな研究スタイルを学び、実践する重要な経験となった。
1980 年代は実験装置が殆ど全て⼿作りで、全て⼿動計測・⼿動記録の時代で、仙台時代は連⽇研究室に泊まり込んでの実験が続いたが、その後 1990 年代に⼊りパソコンが導⼊され⾃動計測の時代になり、さらに図書館で⽂献をコピーしていた時代からインターネットで世界の研究論⽂が瞬時に⼊⼿できる環境になるなど研究環境も⼤きく変化した。また、1980 年代は産学官連携がまだ⼀般的では無い時代
で、⼤学と企業の共同研究は「⼤学教員の魂を売るのか？」という反発が多く、産学官連携を⾏う教員－ 57 －

は肩⾝が狭かった時代だったと⻄澤教授からいつも聞かされていた。それから 40 年経過した現在、産学官連携を⾏わない⼤学教員は「社会の役に⽴っているか？」と肩⾝が狭くなるという 180 度の⼤転換を実感として経験してきた。⼤学における「研究の⾃由」は当然守らなければならないが、社会との連携の上に⼤学が存在するという今の常識は、そんなに昔から存在したのでは無いと⾃分の経験から感じる。しかし研究の本質は、研究者の知的興味、経験や勘による推進が第⼀で有り、現在でも、更に将来もその本質は変化しないと確信している。⼀⽅で、経験の積み重ねは重要だが、逆に経験の無さを⻑所に考え、詳細な⽂献調査や綿密な研究計画と⾃由な発想で研究を進めることも更に重要と考える。その意味で今後の若い研究者の斬新な発想と積極的な⾏動⼒に期待したい。
⼤学運営では、2008 年から教育研究評議員を、2019 年から理事・副学⻑を務め、運営に深く関わってきたが、⼤学組織全体としての教育・研究の質の向上の重要性を改めて感じてきた。特に⼤学における「研究の⾃由」の基本理念を尊重するとともに、国⽴⼤学教員としての恵まれた環境の中で、質の⾼い研究成果の継続的な発信と教育への還元という義務・責任を全教員が認識する必要性を強く感じている。引き続き 2024 年まで理事・副学⻑を務めるが、岩⼿⼤学の教職員、学⽣が同じ⽅向に向かって更に活躍できる環境の整備や組織・教育プログラムの改編に取り組みたい。
岩⼿⼤学に赴任した 1991 年から約 32 年間に、池部研究室の時代から数えて、卒論学⽣ 188 名、修論
学⽣ 80 名、博⼠論⽂学⽣３名（藤根陽介君、⾼橋圭太君、⾼橋裕平君）を育て、学術論⽂を 291 編（その内、first author として 106 編、corresponding author として 51 編）を出版できたことは⼤きな誇りである。それぞれの学術論⽂には深い思い⼊れがあり、⼀緒に苦労して研究した学⽣達の顔が思い出される。
各学術論⽂の出版は、「公共財」としてその時代のその研究分野での新規性を主張する内容が含まれ、それが査読で評価され公表された結果だったと確信している。学術論⽂掲載決定と競争的外部資⾦獲得決定の知らせが届いたときは、努⼒が評価されたという精神的な充実感や満⾜感を味わい、乾杯をし、それが次への活⼒に繋がったことは事実である。様々な企業等との共同研究、受託研究を実施したが、他では実現出来ない研究シーズ、例えば、熱伝導率測定や着磁シミュレーションなどがあったことが相⼿から信頼された結果として実施され成果が創出されたと考えている。2021 年に内藤君が教授に昇任し、今後も私と⼀緒に培った研究マインドを受け継いでくれると思う。今後の活躍を期待したい。
これまでの研究⼈⽣を振り返ると、20 代で学術論⽂が書けなかった悔しさからハングリー精神を持って誰よりも論⽂公表にこだわった事、30 代前半で仙台を離れてから新しい超電導研究の分野に⾶び込
んだ事、そして 30 代中盤に岩⼿⼤に赴任してからパーマネントの安定した職を得て、（今よりは）潤沢な講座費を⾃由に使って、思う存分⾃由な研究を出来たことが⾃分の研究⽣活にとって⾮常に重要な要素だったと感じている。また、これまで⼤学教員として教育研究に携わって来られたのは、様々な関係者、協⼒者があっての事である。今後は⾃分の研究経験を失敗談も含めて若い世代に伝え、励まし、⽀援する役⽬があると考えている。⻄澤研究室での卒論研究で始まった約 40 年の私の研究者⼈⽣は⾮常に充実していたと感じている。関係者、協⼒者の皆様に感謝申し上げる。
令和４年(2022 年) ３⽉
藤代 博之－ 58 －

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1985~1989i ùG¢ŜÃÌD˞GaASa·)ʽ˂ʤʳʋɈƒƞƪ˟ 28Œ
1989~1991i fgU[/y˞Sia·)ɦȚɓ·ĴĖʋƞƪ˟ 32Œ
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BT=5.2 T by MMPSC (2004) M2ÎcB
on GdBaCuO bulk (46mm)
PFM¢śŨū¸ğÆNŜ]´Ƨ´JŦÄũŬŖłŚłƨ

2nd stage���

T2~30K, B2~6.7T“coneshaped”

�
���
�
���
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2005Ê8Ī28ě¿ñěĮLˢɖĆȡ

これは面白い！

˃˖ʳƛƠʅ5 TʋāĀ
ʠ°Ƅ˂˖ʭƠƝʉ{ÒɻʜĜ`Eĳ˞ʤ˚ʭʉzʒʝʜƠå)Ʒɱ{Òɸʝʜ˟15

16

ː˜ʵXļʋʽː

ĶĿģĉ

Bz=5.3TēÔàĿ(ŴżƓƈïŀśŝĽÔàŜŜďŗĽŴżƓƈŗXĘŘōŖéŊ
ũŬŖłőƜƂƚŮĽƙƥſņ²łŖâ(ŏūĽŘłŃ°óņŁūľ
ćŊ(ōőXĘőœŮĊŬwŏŠň³ŜăņĆłŅŉŖňūņĽWāņÿŋŔŖ¦ņ,ŬĽƙƥſŘêŝAŋŃdşőřŪÁňľōŅōĽŁŘŮĆŔŖŇőăĖŝĽ¦ņ#śwŔŖCŤąţŬŖōţŃľŋŃōŖĽƙƥſőœŝ® ŴżƓƈŮ(ūŋŘņ(őľSiĺʋīŌa·)ŰŨ

17˗˚ʻʋşO

18－ 61 －

Without magnetic field

理工学部 吉本先生

Record-high trapped field using FCM and PFM

・自然乾燥では、過飽和と結晶成長が外周部からランダムに発生・結晶粒がランダムで小さい

REBaCuO bulk

親水性基板上の
有機半導溶液10 mm

MgB2 bulk
1 mm・結晶成長が磁場中心から起こり、磁場により結晶成長を制御可能

17.24 T (ISTEC)
17.6 T (Cambridge)
15.1 T (Iwate)

5.2 T (Iwate) on surface
5.3 T (Cambridge) in bulk pair

5.4 T (IFW Dresden) on surface
5.6 T (Iwate) in bulk pair1.61 T (Iwate) on composite
surface
1.1 T (Iwate) on surface

Ț"·˂˖ʭʋ˃˖ʳƛƠʋKȿʅʌɦ¿ñƎʠ˕˜ʿɹʄɬʜɧ

・結晶粒が配列し大きい
・全く新しい応用展開が可能！
10 mm

Pulsed fieldmagnetization (PFM)

これは面白い！

under “Moses effect” in magnetic field
磁場中心(Bz=5.3T)

Field cooledmagnetization (FCM)ɱÛ˞Ȧɬ¶ķ˟ɦ¿ñ ªɱɦFCMʉʙʛREBaCuO˂
˖ʭʅ20 TʠțɮʜāĀƠ˞ƎĩɣāĀƠ˟ʠ°ƄɻʜɷʆʠįÙ˝˛ŌŃƕǱÔʋǿǼɱ­
˛RʝʜɰRʝʈɬɰɦɫʆʌȬ

親水性基板上の
有機半導溶液

1 mm

19

20

2006Ê ¿ñ(Pr1-yREy)1-xCaxCoO3ĉćÏ¥ÇąPrĉiªÅªȸĴĖżåÅªƣ˞Ƅʋˌʼ˕ʢ˖ʯ˜ʳ˟đĂ 49Œ

˛ňɨʈĴĖʋź"·Ƃŭ¯˞ ŅʆʋCwƞƪ˟˛CoƸȻ]żʋŽƐʈȠƦƄȏ˛Țɓ·˂˖ʭĴʋÔƠāĀʉɊɻʜƞƪ˞°ɡʆʱˍ˒˗˜ʱ˓˚˟˛ĘǷźɓĈĴĖʋSǲ¢¦HĉmÝ
ľ¶ĄÂkĕ½úë¶ĄFüĒìľń ńħĿĳŁ¶Ą%ôćøēċëĨĿĤõćðł
ľM1ČĄĊÍëM2Ċ¶Ąć¢¦ĕD#˛ɕÈʉ ɲʈʱˑ˜ˇʈɁ¼˛ǃǉ)ȠƦ˞ÈƠå˛lÔƠåȠƦ˟˛˛˛ŎƙȠƦ˛Pr, CaƸʀɵʅșɷʜ˛ƿîx, yʋɫʜƴDʀɵʅșɷʜ
˛2010ÊÕģɦƅƋɱğ˛Ǚ~ʠýʂʄɬʜƞƪǑɱ¹ʈɬ˞ʹˑ˚ʳ˝˟ľAEáĊªń¹³ĄÄjĕr÷ŁČýĊ¸ÃĐúðnsÃĄł

これは面白い！

˛ƸǂƕʉRE, x, yʠ]ɸɽɿȁĖʠ+ǲɹɦȠƦƄȏʠȧŚ˝

2122ʹʦʯʆʋCwƞƪ˛˛˛˛ŕźŭ¯ɦå§öƲʠ-ɛ
JPSJ 81 (2012) 064709

ŕźŭ¯ǁļɰʚą¯ɹɿPrʤʨ˚ʋ.ēʱ˅ʾʆCoʤʨ˚ʋ.ēKȺʌ(Pr3+0.85Y3+0.15)0.7Ca2+0.3Co3+0.7Co4+0.3O2-3(Pr3+0.59Pr4+0.26Y3+0.15)0.7Ca2+0.3Co3+0.88Co4+0.12O2-3

Pr3.17+
Pr3.29+(T<<TMI)XANES (Pr L3 {mƯ) ŭ¯ at Spring-8ɓǢåɱîʛƮʃɿʕʉʌɦ
.ē]˞.ēĊZ˟ɱșɷʂʄɬʜʋʅʌŷɬɰˬ

3.5

Valence of Pr ion

y=0.075
y=0.15(T>>TMI)˛XǇ{mʳˉʭʾ˖(XAS)ʉʙʛɦPrʤʨ˚.ēʋʱ˅ʾʠƘĄƕʉǹŭɻʜɧ˛ Prʤʨ˚.ēʋʱ˅ʾʆwģʉșɷʜɷʆɱéɸʝʜCoʤʨ˚.ēʋ]ʠɦXAS
ʉʙʛ°ɡƕʉŭ¯ɻʜɧ

Spring-8ĄĉGé (2011~2016)

y=0.075
y=0.15Pr3.17+
Pr3.29+3.3

Pr0.5Ca0.5 Pr3.70+

3.2

XAFS測定 (8K)Pr3.15+
Pr3.27+
Pr3.40+y=0.075
y=0.153.1
3.0

˛2010vĲ=Ƈʉƙȇ−˫Spring-8ʋƞƪǑʠƽɸʝʜ−˫ƌȈɹă÷ɸʝʜ

0

50

100

150

200

250

300

T (K)

2011.3.11東日本大震災

・温度低下と共に、Pr4+(4f1)ピークが増大し、Pr3+(4f2)ピークが減少する。（Prの価数シフトは起こっている）

˛2010ʉʳˉʤ˚ʋƞƪǑɱɻʅʉXASʋ°ɡǁļʠƒǮɹʄɬɿ˞Ɯʚʈɰʂɿ˟ɧ

23

比熱測定

3.4

・TMIよりかなり高温から価数の変化が起こっている。

24－ 62 －

ɷʝʒʅʋPYCCOƞƪʌǁĦʠƉɬɿƞƪ

W¢¦ľľľ(®qĕðĀFõVæPYCCO(®q´[Ĉ`\ľľľľućðŀŀ

薄膜単結晶におけるMISS転移現象
ƤY. Noda, H. Fujishiro, T. Naito, A. Ito, T.Goto, J. Hejtmanek and Z. Jirak
AIP Advances 6 025318 (2016)

薄膜

薄膜

⾯内圧縮

Ƥ H. Fujishiro, Y. Noda, K. Akuzawa, T. Naito, A. Ito, T. Goto, M. Marysko,
Z. Jirak, J. Hejtmanek and K. Nitta
J. Appl. Phys. 121 115104 (2017)

⾯内張⼒

単結晶基板
単結晶基板

伸びる

ne

これは面白い！

縮む
張⼒

In-plane

Inpla

圧縮

Out-of-planeƤMŘŜƗŽƑŰƄƈśŨūI-0ŗĄÉªkŝR3ŏūŅƱƤT×Ř8×ŜĒ½Ś×Ůqŀ§ˍʳ˅ʣʺʾʗǕh]ʉʙʜƑ$ƕʈTXļɱįÙɸʝʜ

25

MZs

26

ĮĺĠ £ĉğĴķĻĿğĸĽŁ2010ł(Pr0.8Y0.2)0.6Ca0.4CoO3

Ƥ]ĞŒŉŗŝÃÌśĔ¸ŮuŎūƤƤƤƤ]ĞŗÅòŏūśŝĒņŅŅū
ƤUŇŚhysteresisŮŃºhŚupturnņ
SrLaAlO4 (SLAO)MƧin-plane
compressive stressƨŜŤŗÅòŌŬūľ

ƤŻƗƛơƥŻƝƢŜƘƟƄƈ
˛°ɡǁļʋǺȼ˛°ɡǁļʋŭ˞ĘɿʈćŁ˟˛˛˛˛˛HTFMLɦHG-TFMʋćŁʉƇɰɸʝʜƤůƊƥƠŮŏūŘºhņ§V

2012 âƉȚɓ·ʉɊɻʜɏ!Ȍ(ASC2012 in Portland, USA)
Dr. Mark AinslieʆʋJ!ɬ
Ģɞʅ6ŸʉJ!ɭɧ
wɺKȿʋƞƪǑʅɫʜɷʆʅňɨʈdiscussionƤę|{²ŜØ`!ŝĽlatticemismatchŜO.ŘŘŦśOUŏūľ
ã;Zs

2013 MarkɱMʕʄƖ¾ʠǾ2015 ǪɱCambridgeʠǾƤę|{²Ŝºhŝ50 nm;ŜèãŜŤŗî«ŌŬĽ100 nmŗŝòťũŬŚłľ

Dr. Mark AinslieɾʋÛɦʉǾ ˞2014~2019: VđˢxɦªƇ˥xʠˣ˥ȪɉCambridgeʐţȲ˟˛˛˛JSTɉŤŅʉă÷(2014~2016)Ɍɦ36ǈʋȉĕʠƒǮ

27

28

CambridgeU[ŘŜ%?ÃÌƧ2013~) ƬƭCavendish Laboratory
˛Maxwell˞MðɆ˟
˛J.J. Thomson, W. Bragg, E. Rutherford, A. Compton,
˛Watson & Crick˛29ʋˁ˜ˈ˖ȖoȖǑʠȣJɹʄɬʜɧ

King’s collegeg[ďĀęaƎƠŷŸƠƥƓ
2015~2016 ªÿɉŤă÷

D.A. CardwellđĂ (ƄUniv. Cambridge vice-chancellor)ƤŋŬţŗƬFðEĽö­ƤÃÌ^Ŝ/Ʃ@(2015)ĽU[ĕ¶ƫ@ŮƪċĒƫċĒ¤Ď(2015, 2016, 2018)ƤCambridgeŜÃÌßƤU[ĕ¶ņi¾bŮðEƤHėøÑŗŃkśĽ%?ÃÌƤõ ŜdiscussionƤšŢċĽ\½ŚƘƥƠŜ ŗÃÌŜøõ

29

30－ 63 －

パブ Eagle

˛ʹˑ˜ʹ˖˛˙ʾʶ˚ɦʭ˕ʺʭʈʇƞƪʋuɉʉɳʃʞɴ

31

32

Ts=40K, Bex=6T, a=4.6e9
Magnetic field

Ts=40K, Bex=6T, a=4.6e9
Temperaturet=0.003s

Magnetic field

10T

80K

3T

80K

0T

40K

0T

40K

33

34

lúðĭĺĝ£¡ŁHTFMLąHG-TFMłĉey (2017~2021)nŝƏƠŽÁÆ]ĞŘŻƗƛơƥŻƝƢŗƖƢƋƟ3Ľ"¬2017.9 5â Æ(MT23;ĖĵĠħĺĥĵł)ĈEą,!
ÿĉ ÆĈëê|8B0Ł:E²áAE"hłõlúðĭĺĝ£¡{Òĕey
2018: ĬĘįĹĦĪ:Î Jĭĺĝ£¡ĻĽġ(HTFML)*!£=ďđčAöć£=ĕ_¯ĈbaüĒ
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ĉ£õ.µćAöć£=&Öõ_¯ĈGŁ9ĄĉfUKÚ>ĉGłğĴķĻĿğĸĽĈďĒGÁGéÀèąÄj¼ë5â

35

t=2s

これは面白い！

ÆĄĉ^QÅ36－ 64 －

TemperatureGÁGéBapp = 3 T

lenscylindercylinderlenscylinder

lens

Bc

Bc
Bex

Bc = 5.5 Tɷʝʒʅʋ°ɡˁ˜ʾ˞¿ñ ȘÛˤˡÊɉʅˢˤ˦F˟˛ĩȦʌ°ɡˁ˜ʾʅʌŷɳɦ!Ȍ˞ ªȬ˟ˁ˜ʾʉʈʂʄɬʜɧ

Bapp = 7 T

Bapp = 5 T

Bc

Bex

Bex

Bc = 7.9 T

Bc = 9.8 T

K. Takahashi, H. Fujishiro, S. Namba and M. D. Ainslie Supercond. Sci. Technol. 34 (2021) 05LT02

37

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学問の自由
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最後に研究者の責任51

Ɩ¾ɣƲÅŅªľÅ−˫1992x

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ƄʋƅÅªȸưˢˢɠȞ53－ 67 －

B: 代表的論⽂（10 編）
1. (D-1) 藤代博之、内藤智之、池部 学、能登宏七、「低温における熱拡散率と熱伝導率の同⼀セッテ
ィング測定」、
低温⼯学 28 (1993) pp. 533-539 (No. 10 paper)
2. (F-17) Hiroyuki Fujishiro, Tatsuya Tateiwa, Atsushi Fujiwara, Tetsuo Oka and Hidemi Hayashi, “Higher
trapped field over 5 Tesla on HTSC bulk by modified pulse field magnetizing”,
Physica C 445-448 (2006) pp. 334-338 (No. 134 paper)
3. (G-1) H. Fujishiro and T. Naito, “Simulation of temperature and magnetic field distribution in superconducting
bulk during pulsed field magnetization”,
Supercond. Sci. Technol. 23 (2010) 105021 (8 pages) (No. 174 paper)
4. (A-41) H. Fujishiro, T. Naito, S. Ogawa, K. Nitta, J. Hejtmanek, K. Knizek and Z. Jirak, “Valence shift of Pr
ion from 3+ to 4+ in (Pr1-yYy)0.7Ca0.3CoO3 estimated by X-ray absorption spectroscopy”,
J. Phys. Soc. Jpn. 81 (2012) 064709 (5 pages) (No. 189 paper)
5. (A-48) Y. Noda, H. Fujishiro, T. Naito, A. Ito, T. Goto, J. Hejtmanek and Z. Jirak, “Electrical resistivity
anomaly in (Pr1-yMy)1-xCaxCoO3 epitaxial films (M = Y, Gd) fabricated by pulsed laser deposition”,
AIP Advances 6 (2016) 025318 (9 pages) (No. 232 paper)
6. (H-1) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A new concept of hybrid trapped field magnet lens
(HTFML)”,
Supercond. Sci. Technol. 31 (2018) 044005 (9 pages) (No. 257 paper)
7. (H-3) Sora Namba, Hiroyuki Fujishiro, Tomoyuki Naito, Mark D Ainslie, Keita Takahashi, “Experimental
realization of a Hybrid Trapped Field Magnet Lens (HTFML) using a GdBaCuO magnetic lens and MgB2
bulk cylinder”,
Supercond. Sci. Technol. Letter 32 (2019) 12LT03 (7 pages) (No. 271 paper)
8. (I-25) Tatsuya Hirano, Yuhei Takahashi, Sora Namba, Tomoyuki Naito and Hiroyuki Fujishiro, “A record-hightrapped field of 1.61 T in MgB2 bulk comprised of copper plates and soft iron yoke cylinder using pulsedfield magnetization”,
Supercond. Sci. Technol. 33 (2020) 085002 (10 pages) (No. 276 paper)
9. (H-8) K. Takahashi, H. Fujishiro and M. D. Ainslie, “A conceptual study of a high gradient trapped fieldmagnet (HG-TFM) providing toward a quasi-zero gravity space on Earth”,
Supercond. Sci. Technol. 34 (2021) 035001 (13 pages) (No. 283 paper)
10. (H-9) K. Takahashi, H. Fujishiro, S. Namba and M. D. Ainslie, “Experimental realization of an all(RE)BaCuO hybrid trapped field magnet lens generating a 9.8 T concentrated magnetic field from a 7 T
external field”,
Supercond. Sci. Technol. 34 (2021) 05LT02 (9 pages) (No. 284 paper)70－ 68 －

1. (D-1) 藤代博之、内藤智之、池部学、能登宏七「低温における熱拡散率と熱伝導率の同⼀セッティング測定」、
低温⼯学 28 (1993) pp. 533-539 (No. 10 paper)71－ 69 －

－ 70 －

－ 71 －

－ 72 －

－ 73 －

－ 74 －

－ 75 －

－ 76 －

2. (F-17) Hiroyuki Fujishiro, Tatsuya Tateiwa, Atsushi Fujiwara, Tetsuo Oka and
Hidemi Hayashi,“Higher trapped field over 5 Tesla on HTSC bulk by modified pulse fieldmagnetizing”,
Physica C 445-448 (2006) pp. 334-338 (No. 134 paper)72－ 77 －

Physica C 445–448 (2006) 334–338
www.elsevier.com/locate/physc

Higher trapped ﬁeld over 5 T on HTSC bulk by modiﬁed pulse
ﬁeld magnetizing
Hiroyuki Fujishiro a,*, Tatsuya Tateiwa a, Atsushi Fujiwara a,
Tetsuo Oka b, Hidemi Hayashi caIwate University, 3-4-5 Ueda, Morioka 020-8551, JapanIMRA Material R&D Co., Ltd., 5-50 Hachiken-cho, Kariya 448-0021, Japanc
Kyushu Electric Power Co., Inc., 2-1-47 Shiobaru, Fukuoka 815-8520, Japanb

Received 21 March 2006
Available online 23 June 2006

Abstract
The trapped ﬁeld BPT ¼ 5:20 T has been realized on the GdBaCuO bulk superconductor by a modiﬁed multi pulse technique combinedwith a stepwise cooling (MMPSC), which surpassed the previous highest record of BPT ¼ 4:47 T. At the ﬁrst stage, a small amount of themagnetic ﬁeld �1 T was trapped at the bulk center with a concave ﬁeld distribution at a high starting temperature Ts � 45 K by the lowpulse ﬁeld application Bex � 4.5 T. Following the ﬁrst stage, the higher ﬁeld of Bex � 6.7 T was applied at a lower Ts � 30 K at the second
stage. The concave trapped ﬁeld proﬁle over the bulk at the ﬁrst stage and the optimization of the higher applied pulse ﬁeld at the second
stage are key points to enhance BT above 5 T.
 2006 Elsevier B.V. All rights reserved.
PACS: 74.25.Bt; 74.80.Bj; 74.60.Ge
Keywords: Pulse ﬁeld magnetizing; Temperature rise; Bulk superconductor; Trapped ﬁeld

1. Introduction
The pulse ﬁeld magnetizing (PFM) on high-Tc bulks has
been recently intensively investigated instead of the ﬁeld
cooled magnetizing (FCM) because of the relatively compact, inexpensive and mobile setup [1]. However, thetrapped ﬁeld BPT by PFM had been pretty smaller than thatattainable by FCM at low temperatures possibly due to thelarge temperature rise DT by the dynamical motion of themagnetic ﬂux. The highest BPT value ever reported had been
3.80 T on the SmBaCuO bulk at 30 K by an improved iterative pulse ﬁeld magnetization method with reduced amplitude (IMRA) [2]. We have systematically measured thetime evolution of the temperature rise DT(t) on the surfaceof the cryo-cooled REBaCuO bulks during the PFM and*

Corresponding author. Tel./fax: +81 19 621 6363.
E-mail address: fujishiro@iwate-u.ac.jp (H. Fujishiro).

investigated the relation between DT and BPT [3–5]. The heatgeneration results from both the pinning loss Qp related to
the ﬂux trapping and the viscous loss Qv related to the ﬂux
movement. The successive pulses with the same strength
make the DT value decrease and the BPT value increase withincreasing number of the pulse application. The loweringof the bulk starting temperature Ts is expected to resultin a higher BPT due to the enhanced pinning force Fp but
it also brings about a larger DT due to an increase of Qp
and a decrease of the speciﬁc heat C(T). As a result,
BPT at Ts = 10 K was not enhanced contrary to our expectation [6]. Recently, we proposed a new PFM technique
named as a modiﬁed multi-pulse technique combined witha stepwise cooling (MMPSC) [7]. This technique consists of
two stages; ﬁrstly, a small amount of magnetic ﬁeld
(BPT � 1 T) is trapped in the bulk center by applying a lower
ﬁeld Bex(1) � 4.5 T at a higher temperature Ts(1) � 45 K,
realizing a concave trapped ﬁeld distribution over the bulk

0921-4534/$ - see front matter  2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.physc.2006.04.077－ 78 －

H. Fujishiro et al. / Physica C 445–448 (2006) 334–338

sample. Secondly, the bulk is cooled down to Ts(2) � 30 K
and the higher pulse ﬁelds of Bex(2) � 6.7 T are applied
twice. As a result, we obtained BPT ¼ 4:47 T on the surfaceof the GdBaCuO bulk, which was the highest record using
PFM technique at that time [8]. The reduction of DT due tothe already trapped ﬂux at the ﬁrst stage and the application of the higher Bex(2) at the second stage are key points
to enhance BPT .
In this paper, we inquire into this technique and report
the renewed highest BPT value of 5.20 T by the MMPSC
technique. We elucidate the importance of the optimizationof Bex(2) at the second stage and investigate the eﬀect of thestainless steel ring set onto the bulk disk on the BPT value.
2. Experimental
A highly c-axis oriented GdBaCuO bulk disk (45 mm indiameter and 15 mm in thickness, Nippon Steel Co., Ltd.)was used. The experimental setup around the bulk is shownin the inset of Fig. 1(a). The stainless steel ring with 4 mm
in thickness and 15 mm in height was tightly set onto thebulk disk using Apiezon-N grease in order to reduce DT
during PFM [8]. The bulk with the ring was stacked on
the soft-iron disk on the cold stage of the GM cycle helium
refrigerator and was magnetized using a solenoid-type
pulse coil dipped in liquid N2 with a soft-iron cylinder[7]. Three Hall sensors (F.W. Bell, model BHA 921) were

Fig. 1. The applied ﬁeld [l0Ha(t)] and the local ﬁelds [BL(C)(t), BL(C)(t),
BL(E)(t)] for RUN-1 after applying the (a) pulse No. 1 and (b) pulse No. 3.

335

adhered to the position C (bulk center), M (8 mm distantfrom the bulk center) and E (16 mm distant from the bulk
center) and the time evolutions of the local ﬁelds [BL(C)(t),
BL(C)(t) and BL(E)(t)] were monitored on a digital oscilloscope. The applied ﬁeld l0Ha(t), of which the maximum
strength was deﬁned as Bex, was monitored by the current
I(t) ﬂowing through the shunt resistor. The rising time ofthe pulse ﬁeld was 13 ms and the duration was �80 ms.
The bulk temperature T(t) was measured at the position
T using a ﬁne thermocouple.
3. Results and discussion
We have performed three MMPSC runs (RUN-1–
RUN-3). Table 1 summarizes the initial conditions [Tsand Bex] and the results [Tmax, DTmax and BT(C)] for eachrun, where BPT means BL (t ! 1). For RUN-1, at the ﬁrst
stage, the pulse ﬁeld of Bex(1) = 4.8 T was applied twice(pulse No. 1 and No. 2) at Ts(1) = 47 K. Then the bulk
was cooled down to Ts(2) � 28 K and the higher
Bex(2) � 6.7 T was applied twice at the second stage (pulse
No. 3 and No. 4). The highest BPT ¼ BT ðCÞ ¼ 5:20 T was
attained for the pulse No. 4. The ﬁrst stage procedure of
RUN-2 and RUN-3 was performed under the similar conditions to that of RUN-1 and, for the second stage, thehigher Bex(2) (=7.01 T for RUN-2) and lower Bex(2)(=6.04 T for RUN-3) were applied in order to clarify theimportance of the strength of Bex(2). In Table 1, the initialconditions and the results using the same bulk without thestainless steel ring are also shown as RUN-0, in which
BPT ¼ 4:47 T was obtained [7].
Figs. 1(a) and (b) show the time dependences of theapplied ﬁeld l0Ha(t) and the local ﬁelds [BL(C)(t),BL(M)(t), BL(E)(t)] for RUN-1 after applying the pulse
No. 1 and No. 3, respectively. BL(E)(t), BL(M)(t), andBL(C)(t) rise up in this order, take a maximum and thenslowly decrease to a ﬁnal stable value. The maximum valueof BL(E)(t) is 4.0 T but that of BL(C)(t) reaches only about
0.9 T. The maximum temperature rise DTmax (=18 K) takes
place, which may mainly come from the heat generation
due to the ﬂux trapping. For the pulse No. 2, the maximumof BL(E)(t) decreases to 2.9 T and DTmax also decreases to
5 K due to the already trapped ﬂuxes which obstruct the
intrusion of the magnetic ﬂux. BT(C) shows a slightincrease to 1.10 T but the BT(M) and BT(E) are nearly
unchanged, both of which are higher than BT(C). For thepulse No. 3 as shown in Fig. 1(b), the maximum of BL(E)(t)remains at 4.2 T, while that of BL(C)(t) increases to 6.0 T
and BPT ¼ BT ðCÞ survives at 5.12 T. These results comefrom the DT reduction due to the trapped ﬂuxes during
the ﬁrst stage and the small DTmax (=29 K) and low Tmax(=57 K) prevent the escape of the magnetic ﬂuxes fromthe bulk. For the pulse No. 4, BPT ¼ BT ðCÞ slightly increases
to 5.20 T.
Figs. 2(a) and (b) present the time evolution of the local
ﬁeld BL(t) as a function of the distance along the radiusdirection on the bulk for the pulse No. 1 of RUN-1 for－ 79 －

336

H. Fujishiro et al. / Physica C 445–448 (2006) 334–338

Table 1
The initial conditions [Ts, Bex] and the results [Tmax, DTmax, ﬁnal BPT ] of three MMPSC runs; the RUN-0 shows the previous results in which BPT ¼ 4:47 T
was attained [7]
Run

RUN-1
RUN-2
RUN-3
RUN-0

First stage
Ts(Bex)Tmax(DTmax)
Ts(Bex)Tmax(DTmax)
Ts(Bex)Tmax(DTmax)
Ts(Bex)Tmax(DTmax)

Final BPT

Second stage

Pulse No.1

Pulse No. 2

Pulse No. 3

Pulse No. 4

47 K (4.80 T)
65 K (18 K)
47 K (4.80 T)
65 K (18 K)
46 K (4.52 T)
64 K (18 K)
45 K (4.54 T)
62 K (18 K)

47 K (4.80 T)
52 K (5 K)
48 K (4.94 T)
52 K (4 K)
46 K (4.52 T)
50 K (4 K)
48 K (4.60 T)
53 K (5 K)

28 K (6.73 T)
57 K (29 K)
27 K (7.01 T)
59 K (32 K)
29 K (6.04 T)
49 K (20 K)
29 K (6.72 T)
58 K (29 K)

28 K (6.56 T)
50 K (22 K)
29 K (6.72 T)
53 K (24 K)
30 K (6.87 T)
52 K (22 K)
29 K (6.59 T)
53 K (24 K)

5.20 T
3.02 T
4.10 T
4.47 T

Fig. 2. The time evolution of the local ﬁeld BL(t) as a function of the distance along the radius direction for the pulse No. 1 of RUN-1 for the (a) ascending
and the (b) descending processes.

the ascending and descending processes, respectively, bothof which are reconstructed on the basis of Fig. 1(a). For the
ascending process, the ﬂux intrusion starts to increase fromthe periphery and the small amount of the ﬂuxes arrives atthe bulk center. After the l0Ha(t) value takes a maximum
at t = 13 ms, the intruded ﬂuxes gradually escape in theregion outer than r = 10 mm but the local ﬁelds at positions C and E continue to increase slightly. If the BT proﬁleis assumed to be symmetrical along the circumferential
direction, it should be noted that the BT proﬁle for the ﬁrst
stage shows the concave and ‘‘M-shaped’’ one. This BT distribution must be a key point to bring about the trapped
ﬁeld higher than 5 T at the second stage.
Figs. 3(a) and (b) show the similar BL(t) proﬁle for thepulse No. 3 (Bex = 6.73 T) of RUN-1 for the ascending
and descending processes, respectively. BL(E)(t) increases
but BL(C)(t) and BL(M)(t) hardly change for the ascending
process. For the descending process, however, BL(C)(t)sharply increases just after l0Ha(t) takes a maximum andBL(M)(t) also slightly increases and the conical trapped
ﬁeld distribution with BL(C) > BL(M) > BL(E) is obtained.

These behaviors suggest that the already trapped ﬂuxes inthe ﬁrst stage are pushed into the bulk center and thatthe additional ﬂuxes are supplied from the peripheral
region. The ‘‘M-shaped’’ proﬁle in the ﬁrst stage changes
to the ‘‘cone-shaped’’ one at Ts � 30 K for the pulse No.
3 with Bex = 6.73 T. It was pointed out in the previous
paper [9] that the height of the cone (=BT(C)) at the second
stage depends on the height of the edge in the ‘‘M-shaped’’
proﬁle; BT(E) should be higher and BT(C) should be lower
at the ﬁrst stage.
Figs. 4(a) and (b) present the time dependences of theapplied ﬁeld and the local ﬁelds for RUN-2 and RUN-3
on applying the pulse No. 3, respectively. In RUN-2, where
Bex = 7.01 T of the pulse No. 3 is higher than that in RUN1, all the maximum values of local ﬁelds, especially
BL(M)(t), increase. Then BL(C)(t) cannot maintain thehigher value and drastically decreases for t > 60 ms by aspontaneous ﬂux jump. As a result, the trapped ﬁelds atthe positions C, M and E decrease to �2 T and the large
heat generation should be the origin for the depression.
For RUN-3 shown in Fig. 4(b), where lower pulse ﬁeld

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H. Fujishiro et al. / Physica C 445–448 (2006) 334–338

337

Fig. 3. BL(t) as a function of the distance along the radius direction on the bulk for the pulse No. 3 of RUN-1 for the (a) ascending and the (b) descending
processes.

Fig. 5. The time dependences of temperature T(t) at position T after thepulse No. 3 application of each run.

Fig. 4. The time dependences of the applied ﬁeld and the local ﬁelds for(a) RUN-2 and (b) RUN-3 after applying the pulse No. 3.

of Bex = 6.04 T was applied, the increase of the BL(t) at
each position is small and the BT(C) value attains only
3.6 T with a round shaped BT distribution.
Finally we comment on the eﬀect of the stainless steel
ring. Fig. 5 shows the time dependences of temperatureT(t) after the pulse No. 3 application of each run. For
RUN-1 to RUN-3, T(t) rises up, takes a maximum at

t = 2 s and then slowly decreases. The local heat generationand the large temperature rise must mainly occur in the
inner part of the bulk within the pulse duration t  0.1 s,
but the temperature change is observable with a long timedelay determined by the thermal diﬀusivity. The maximum
temperature rise DTmax increases with increasing Bex of thepulse No. 3. T(t) of RUN-0 without stainless steel ring is
also shown in Fig. 5 for comparison. It is to be noticed that
T(t) for RUN-0 is much diﬀerent; T(t) slowly increases andtakes a maximum at t  7 s in spite of the identical DTmax
and Tmax values to those in RUN-1. These results suggestthat the heat propagation changes owing to the metal ringsetting and, as a result, the BPT is enhanced from 4.47 T to
5.20 T.
In summary, we performed the MMPSC method on the
GdBaCuO bulk under several conditions and clariﬁed what
are the important factors to enhance BPT over 5 T. At theﬁrst stage in the MMPSC process, the ‘‘M-shaped’’ trapped
ﬁeld proﬁle should be realized on the bulk; BT(C) at thebulk center should be as low as 1 T and the barrier height
BT(E) at the periphery region must be enhanced to 2.5–3 T.

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H. Fujishiro et al. / Physica C 445–448 (2006) 334–338

At the second stage at lower Ts, the optimum higher ﬁeld
Bex, which is 6.7 T for this bulk, should be applied. The
BPT value increased from 4.47 T to 5.20 T as a result of
the stainless steel ring setting onto the bulk disk. The
microscopic change in the heat propagation should takeplace by the ring setting onto the bulk. The detailed study
is in progress.
References[1] U. Mizutani, H. Hazama, T. Matsuda, Y. Yanagi, Y. Itoh, K. Sakurai,
A. Imai, Supercond. Sci. Technol. 16 (2003) 1207.
[2] Y. Yanagi, Y. Itoh, M. Yoshikawa, T. Oka, T. Hosokawa, H.
Ishihara, H. Ikuta, U. Mizutani, in: T. Yamashita, K. Tanabe (Eds.),

Advances in Superconductivity XII, Springer-Verlag, Tokyo, 2000,
p 47.
[3] H. Fujishiro, K. Yokoyama, T. Oka, K. Noto, Supercond. Sci.
Technol. 17 (2004) 51.
[4] H. Fujishiro, M. Kaneyama, K. Yokoyama, T. Oka, K. Noto, Jpn. J.
Appl. Phys. 44 (2005) 4919.
[5] H. Fujishiro, K. Yokoyama, M. Kaneyama, M. Ikebe, T. Oka, K.
Noto, Physica C 426–431 (2005) 594.
[6] K. Yokoyama, M. Kaneyama, H. Fujishiro, T. Oka, K. Noto, Physica
C 426–431 (2005) 671.
[7] H. Fujishiro, M. Kaneyama, T. Tateiwa, T. Oka, Jpn. J. Appl. Phys.
44 (2005) L1221.
[8] H. Fujishiro, K. Yokoyama, M. Kaneyama, T. Oka, K. Noto, IEEE
Trans. Appl. Supercond. 15 (2005) 3762.
[9] H. Fujishiro, M. Kaneyama, T. Tateiwa, T. Oka, to be published in J.
Phys. Conf. Series (2006).

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3. (G-1) H. Fujishiro and T. Naito,“Simulation of temperature and magnetic field distribution in superconducting
bulk during pulsed field magnetization”,
Supercond. Sci. Technol. 23 (2010) 105021 (8 pages) (No. 174 paper)73－ 83 －

IOP PUBLISHING

SUPERCONDUCTOR SCIENCE AND TECHNOLOGYSupercond. Sci. Technol. 23 (2010) 105021 (8pp)

doi:10.1088/0953-2048/23/10/105021

Simulation of temperature and magnetic
field distribution in superconducting bulk
during pulsed field magnetization
Hiroyuki Fujishiro and Tomoyuki Naito
Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan
E-mail: fujishiro@iwate-u.ac.jp

Received 4 July 2010, in final form 3 September 2010
Published 17 September 2010
Online at stacks.iop.org/SUST/23/105021
Abstract
A theoretical simulation of electromagnetic and thermal fields was performed for a cryocooled
superconducting bulk disc after applying a magnetic pulse. The results of the simulation
qualitatively reproduced the experimental ones for the time and applied field dependences of thetrapped field Bz and the temperature T on the bulk surface. For magnetic pulse application witha rise time of τ = 0.01 s, the magnetic flux propagation was about two orders of magnitude
faster than the heat propagation because of the low thermal conductivity of the bulk. The results
show that the intruding magnetic flux escaped because of the delayed temperature rise. For alonger magnetic pulse application with τ = 1 or 10 s, the flux propagation speed becomes slow
and approaches the heat propagation speed. In this case, the magnetic flux escape attributable tothe flux creep becomes small and a higher trapped field can be achieved. The method of
exploring the enhancement of the trapped field using pulsed field magnetization is discussed.

1. Introduction

new PFM technique named modified MPSC (MMPSC) [6] andsuccessfully realized a highest field trap of Bz = 5.20 T on a
45 mm GdBaCuO bulk at 30 K [7], which is a record-highvalue by PFM to date. However, experimental research has
been limited. Results have shown little progress to explore theenhancement of the trapped field using PFM. It is necessary
to use a theoretical simulation to elucidate the multi-physics inthe bulk during PFM.
Several studies of theoretical simulations for PFM havebeen reported. Many of the studies were performed underconditions in which the bulk was immersed in liquid nitrogen.
Simulations have been performed also for cryocooled bulks;
Kajikawa et al reported theoretical results of the MMPSC
method, in which the experimental results were reproduced
qualitatively through the simulation [8]. Komi et al reported
magnetic and thermal fields during PFM in a cryocooled
bulk with inhomogeneous superconducting properties [9]. We
investigated heat propagation in drilled holes in the bulk bothexperimentally [10] and theoretically [11]. The results suggestthat the heat generation took place adiabatically because ofits greater heat generation than the cooling power of therefrigerator.
As described in this paper, we constructed the frameworkof the theoretical simulation in the superconducting bulk with

Recently, pulsed field magnetization (PFM) for REBaCuO
bulk (RE: rare earth element or Y) has been investigatedintensively for practical applications as a substitute forfield-cooled magnetization (FCM) because PFM is an
inexpensive and mobile experimental set-up with no need fora superconducting magnet. The trapped field Bz achievable
by PFM is nonetheless lower than that achievable by FCM
because of the large temperature rise caused by the dynamical
motion of the magnetic flux. Several approaches have been
performed and have succeeded in enhancing Bz including
an iteratively magnetizing pulsed field method with reducing
amplitude (IMRA) [1] and a multi-pulse technique with stepwise cooling (MPSC) [2]. We have experimentally examined
the time and spatial dependences of the temperature T (t, x),local field Bz (t, x), and the trapped field Bz on the surface of
cryocooled REBaCuO bulks during PFM for various starting
temperatures Ts and applied fields Bex [3–5]. To enhance Bz ,it is believed that the reduction in temperature rise �T andthe lowering of Ts are effective because of the enhancementof the critical current density Jc , similar to the case for FCM.
Considering the obtained experimental results, we proposed a
0953-2048/10/105021+08$30.00

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Supercond. Sci. Technol. 23 (2010) 105021

H Fujishiro and T Naito

Their fundamental equations on the axisymmetriccoordinate are as follows.




∂A
∂
∂ ν ∂
(r A) +
ν
= J0 + J(1)∂r r ∂r
∂z
∂z




∂
∂T
1 ∂
∂T
∂T
=
r κab
+
κc
+ Q. (2)
ρC
∂t
r ∂r
∂r
∂z
∂z

Therein, A represents the magnetic vector potential, J0 is theforced current density or coil current density, J denotes thesuperconducting current density or induced current density,
and Q signifies the heat generation. In equation (2), T
denotes the temperature, C is the specific heat, and κab andκc respectively denote the thermal conductivity in the ab -plane
and along the c-axis.
The J value is given as

Figure 1. Structure and dimensions around the bulk and solenoid
copper coil for pulsed field magnetization (PFM). The 1 mm thickspacing plate with thermal conductivity of κcont was placed between
the bulk and the cold stage of the refrigerator, which imaginarily
represents the cooling power of the refrigerator and the thermal
contact of the bulk on the cold stage.

J = σ E = −σ

∂A
,
∂t

(3)

where E is the electric field and σ is the electricalconductivity. Then FEM analysis of the coupled problem withelectromagnetic field and heat diffusion was performed.
The power-n model was used to describe the nonlinear E –J characteristic in superconducting bulk, as nJE = Ec,(4)Jchomogeneous superconducting properties after a magnetic
pulse application using the finite element method (FEM). We
reproduced the experimental results using the simulation. We
also investigated the effect of a magnetic pulse application witha longer rise time of τ = 1 or 10 s on the Bz (t) and T (t) values
than those using a magnetic pulse with τ = 0.01 s, which
was used experimentally because the long pulse application
enhanced the trapped field experimentally [12]. The direction
to explore the enhancement of the trapped field by PFM is
discussed herein.

where Jc is the critical current density and E c is the referenceelectric field. The magnetic field dependence of the Jc0 was
described using the Kim model [13] as

Jc = Jc0

B0,|B| + B0

(5)

where Jc0 is Jc for B = 0 and B0 is constant. The temperaturedependence of Jc0 is described by the following equation,

2. Modelling and theoretical simulation

Jc0 = α 1 −Based on our experimental set-up around the bulk [5], theframework of the theoretical simulation was constructed. A
schematic view is presented in figure 1. A superconducting
bulk disc of 46 mm diameter and 15 mm thickness was stacked
on the cold stage of a refrigerator in a vacuum chamber andcooled to the starting temperature Ts = 40 K. We set the
spacing plate with thermal conductivity κcont between the bulk
and the cold stage to 1 mm thickness, which imaginarily
represents both the cooling power of the refrigerator and thethermal contact. Then κcont was set as 0.5 W mK−1 basedon the experimental results of T (t) on the bulk surface [6].
In the simulation, the bulk was magnetized using a solenoidtype copper coil (82 mm I.D., 116 mm O.D., and 50 mm
height). Physical phenomena during PFM are describedusing electromagnetic and thermal fields. The equations andparameters were taken from [9]. Commercial software, PhotoEddy, combined with Photo-Thermo (Photon Ltd, Japan),
was used for analyses of the magnetic field and temperature
distribution in superconducting bulk during PFM.



T
Tc

2  32,(6)

where Tc is the critical temperature (=92 K) at B = 0 and
α is constant. Heat generation Q in the conductor is given as
Q = J E . Iterative calculations were performed to obtain theconvergence of σ in the superconductor at each time step.
The applied pulsed field Bex (t) with the rise time of τ =0.01 s was approximated in the following equation:


t
t
.
Bex (t) = Bex exp 1 −(7)ττThe numerical values for the parameters used in the simulation
are presented in table 1. The κab , κc and C values were
presumed to be temperature-independent for simplicity.

3. Example of experimental results
Let us show an example of the experimental results of thetrapped field on the bulk magnetized by PFM. Figure 2(a)2

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H Fujishiro and T Naito

Figure 2. Example of experimental results for the trapped field on the GdBaCuO bulk magnetized by PFM [4]. (a) Trapped field Bz (r = 0) at
the centre of the bulk at various starting temperatures Ts after applying a pulsed field Bex with a rise time of τ = 0.01 s. (b) Cross-section of
the Bz profiles for various applied pulsed fields Bex at Ts = 70 K. In the inset, an example of the two-dimensional Bz profile is shown for
Bex = 2.66 T.

the inset, an example of the two-dimensional Bz profile isshown for Bex = 2.66 T. The trapped field profile changes
from a concave shape for Bex  3.84 T to a convex shapefor Bex  4.52 T. For lower Ts = 40 K, similar changes of
the Bz profile were observed as a function of Bex (not shown).
However, Bz (r = 0) at the bulk centre was small, even if apulsed field with identical strength was applied as that at 70 K.
The maximum Bz (r = 0) increases to 1.8 T for Bex = 6.29 T,
but the convex profile cannot be realized because of the strong
pinning force at low temperatures.

Table 1. Numerical values for parameters used in the simulation.
SymbolParameter

Value

Tc

Transition temperature inequation (6)Mass density of bulk inequation (2)Specific heat of bulk inequation (2)Thermal conductivity ofbulk along the ab-plane inequation (2)Thermal conductivity ofbulk along the c-axis inequation (2)n -value in equation (4)Constant in equation (4)Constant in equation (5)Constant in equation (6)Electrical conductivity( T > Tc ) in equation (3)Rise time of the pulse inequation (7)Thermal conductivity ofspacing plate

92 K

ρ
C
κab
κc
n
Ec
B0
α
σ
τ
κcont

5.9 × 103 kg m−3
1.32 × 102 J kg−1 K−1
20 W mK−1
4 W mK−1

4. Results of simulation and discussion
4.1. Applied field dependence of trapped field

8
1 × 10−6 V m−1
1.3 T
0.23–1.83 × 109 A m−2
1 × 103 S cm−1

Figure 3(a) depicts the results of the simulation of the trappedfield Bz (r = 0) at the centre of the bulk surface as a function of
the applied field Bex for various α values in equation (6). The
Jc0 values at 40 K for α = 1.83 × 109 , 9.2 × 108 , 4.6 × 108
and 2.3 × 108 are, respectively, Jc0 = 1.33 × 109 , 6.6 × 108 ,3.3 × 108 and 1.6 × 108 A m−2 . The Jc0 values for a typicalsuperconducting bulk are, respectively, 2–3 × 109 A m−2 at
40 K and 1–2 × 108 A m−2 at 77 K [14]. Therefore, α =1.83 × 109 is a typical value of the bulk at 40 K. In allcases, the Bz (r = 0) starts to increase concomitantly withincreasing applied pulsed field Bex , becomes maximum andthen decreases with a further increase in Bex . The criticalC
applied field Bex, at which the magnetic flux starts to trap at
the bulk centre, increases concomitantly with increasing α .
The results presented in figure 3(a) can also be interpreted as
the Ts dependence of Bz (r = 0) for various Bex for the bulk
with constant α , which is consistent with the experimental
results shown in figure 2(a). Although the trapped field BzFC
achieved by FCM increases concomitantly with increasing
Jc , the trapped field Bz achieved by PFM is not necessarily
enhanced for higher Jc because of the large temperature rise,as described in section 4.2.

0.01, 1, 10 s
0.5 W mK−1

shows the trapped field Bz (r = 0) at the centre of
the GdBaCuO bulk (45 mm in diameter and 18 mm inthickness) after applying a pulsed field Bex at various starting
temperatures Ts [4]. The rise time τ of the pulsed field was
0.01 s. Bz (r = 0) at Ts = 70 K starts to increase for Bex 
2.7 T, takes a maximum at Bex = 4.4 T and then decreases
with increasing Bex . For lower Ts , the applied field, at which
the magnetic flux starts to be trapped at the bulk centre, andthe peak of the Bz (r = 0) value increase with decreasing Ts
because of the enhancement of the critical current density Jc .
Figure 2(b) presents a vertical cross-section of the Bz (r )profiles after applying a pulsed field at Ts = 70 K [4]. In
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H Fujishiro and T Naito

Figure 3. (a) Results of simulation of applied field dependence of the trapped field Bz at the bulk centre (r = 0) for various α valuesCfor each α( Ts = 40 K). The inset shows the time dependence of the normalized magnetic pulse. Arrows indicate the critical applied field Bex
value (see the text). (b) Cross-section of the trapped field profiles for α = 4.6 × 108 at Ts = 40 K as a function of Bex (simulation).

t = 0.1 s and then decreases gradually to Bz = 1.7 T at thesteady state.
In figure 4(b), the temperature T (t) at the bulk peripheryincreases gradually with time at the ascending stage, e.g. T =78 K at t = 0.01 s. However, the temperature for r = 0
remains as 40 K. At the descending stage, the generated heatdiffuses to the bulk centre gradually. In line with the isothermal
temperature profile along the r -direction at t = 5 s, thetemperature decreases concomitantly with increasing time. In
this case, a temperature gradient exists along the z -direction
because the bottom of the spacing plate was fixed at 40 K.
Figures 5(a) and (b) show the time dependence of local
fields B(r, t) and the temperatures T (r, t) at r = 0, 10 and
20 mm on the bulk surface, respectively, which were re-plottedfrom figure 4. The time dependence of the magnetic pulse
Bex (t) is also shown. In figure 5(a), the local field Bz (t) near
the bulk periphery starts to increase rapidly; it then decreases.
On the other hand, Bz (t) at the inner position rises with a timelag, decreases gradually, and approaches the final value fort > 10 s.
In figure 5(b), the temperature T (t) near the bulk
periphery starts to rise rapidly. It then decreases. The timeat which the temperature starts to rise becomes delayed at
the inner measuring position. At the bulk centre (r = 0),
T (t) takes a maximum at t = 7 s and is independent of themeasuring position. It is noteworthy that the time at whichBz (t) becomes maximum is about two orders of magnitude
faster than the time at which T (t) reaches its maximum value.
These results are attributable to the lower thermal conductivityof the bulk and smaller heat transfer to the cold stage. After
Bz (t) reaches its maximum value, T (t) becomes maximum.
As a result, the local field decreases because of the flux creep.
For t > 7 s, Bz (t) becomes constant because the temperature
decreases.
Figures 6(a) and (b) respectively show a simulation of thetime dependence of the local field Bz (t) and temperature T (t)at the centre of the bulk surface (α = 4.6 × 108 ) after applying
pulsed fields of Bex = 5, 6 and 8 T. The peak height of Bz (t)In the simulation, the maximum temperature Tmax (r = 0)
at the centre of the bulk surface increased concomitantly withincreasing Bex , which was independent of the α value. These
results suggest that the generated heat was determined by thestrength of Bex and that the temperature rises adiabaticallybecause of the smaller heat transfer to the cold stage. The
result reproduces the experimental results, in which Tmax for
the YBaCuO bulk with a lower pinning force is nearly the sameas that for the GdBaCuO bulk with a higher pinning force [5].
Figure 3(b) presents a cross-section of the trapped fieldBz (r ) profile for α = 4.6 × 108 for various applied fields Bex .
The positions of r = 0 and 23 mm are, respectively, the centre
and edge on the bulk surface. The Bz (r ) profile changes fromconcave for lower Bex to convex for higher Bex and then theBz (r = 0) value decreases with further increases in Bex . Thesebehaviours are apparent for each α value and are consistent
with the experimental ones as shown in figure 2(b). In thisway, the results of the numerical simulation reproduced theexperimental ones qualitatively.
4.2. Time dependence of local field and temperature
Figures 4(a) and (b) respectively show the time evolution andspatial distribution of the local magnetic field Bz (t, r ) andthe temperature T (t, r ) on the bulk surface after applying apulsed field of Bex = 6 T for α = 4.6 × 108 ( Jc0 =3.3 × 108 A m−2 ). The left and right parts of each figure
respectively show ascending (t  0.01 s) and descending(t  0.01 s) stages. For the ascending stage, the magnetic
flux intrudes gradually into the bulk from the bulk peripheryand the magnetic gradient increases with approach to the bulk
centre at t = 0.01 s. It should be noted that the magnetic
flux concentration took place outside the bulk because of the
diamagnetism of superconducting bulk, and that a magnetic
field of 6.8 T was applied along the z -axis at r = 23 mm. For
the descending stage (t  0.01 s), the magnetic field decreased
gradually at the outer region with increasing time. On the other
hand, the local field near the bulk centre increases to 3 T at
4

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H Fujishiro and T Naito

Figure 4. Time and distance dependence of (a) the local magnetic field B(t, r ) and (b) the temperature T (t, r ) on the bulk surface after
applying a pulsed field of Bex = 6 T at Ts = 40 K for α = 4.6 × 108 . The left and right parts of each figure respectively show the ascending(t  0.01 s) and descending (t  0.01 s) stages.

Figure 5. Time dependence of (a) the local field Bz (t) and (b) the temperature T (t) for r = 0, 10 and 20 mm on the bulk surface after
applying a pulsed field of Bex = 6 T (α = 4.6 × 108 ).

increases concomitantly with increasing Bex . However, thetime at which Bz (t) takes a maximum value is about 0.05 s; it
is independent of Bex . In fact, Bz (t) approaches the final value
for t > 10 s. The temperature T (t) increases and reaches its
peak at about 7 s, which is independent of Bex . The peak heightof T (t) increases with increasing Bex .
The results of the simulation shown in figures 5 and 6
well reproduce the experimental results reported in previous
papers [4, 5]. It is noteworthy that the simulation model used
for this study can qualitatively demonstrate Bz (t) and T (t) inthe bulk. However, some differences from the experimental
results do exist. In the experiments at Ts = 40 K, the magnetic
flux started to intrude and trap from 3 T at the centre of thebulk with 45 mm diameter and 15 mm thickness, which was as
high-performance as α = 1.83 × 109 [4]. In existing bulks,

an inhomogeneous Jc distribution exists, which arises fromthe crystal growth mechanism. The magnetic flux intrudes
through the lower Jc paths and traps them inhomogeneously.
The numerical simulation must be performed for the bulk withan inhomogeneous Jc distribution.
4.3. Application of long magnetic pulse
An extremely useful PFM technique is zero-field cooling(ZFC), of which the ascending and descending periods areof the order of 100–1000 s. Considering the Bean model,a magnetic field resembling that by FCM can be trapped by
ZFC after a magnetic field twice as high as that for FCM
is applied. We have reported that a trapped field Bz can beenhanced using a longer ascending magnetic pulse [12]. In
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Figure 6. Time dependence of (a) the local field Bz (t) and (b) the temperature T (t) at the centre of the bulk surface after applying a pulsed
field of Bex = 5, 6 and 8 T (α = 4.6 × 108 ).

Figure 7. (a) Applied field dependence of the trapped field Bz (r = 0) at the bulk centre for τ = 0.01, 1 and 10 s. (b) Cross-section of thetrapped field profiles for τ = 10 s as a function of applied pulsed field Bex (α = 1.83 × 109 ).

section 4.2, we presented a simulation for the bulk with lower
Jc (α = 4.6 × 108 ; Jc0 = 3.3 × 108 A m−2 at 40 K) using apulsed field with a rise time of τ = 0.01 s. In this subsection,
we present a simulation of Bz on the bulk with higher Jc(α = 1.83 × 109 ; Jc0 = 1.33 × 109 A m−2 at 40 K) using
a longer magnetic pulse field. We discuss the origin of the
Bz enhancement using a longer pulsed field and discuss the
direction for the Bz enhancement using PFM.
Figure 7(a) presents the calculated trapped field Bz (r = 0)on the bulk surface (α = 1.83 × 109 ) as a function of an appliedfield Bex with a rise time of τ = 1 and 10 s. The results forτ = 0.01 s are also shown. With increasing rise time τ , themaximum trapped field Bz (r = 0) increases concomitantlyC, at whichwith increasing τ . In addition, the applied field Bex
the magnetic flux starts to be trapped at the bulk centre,
decreases. For example, for τ = 10 s, Bz (r = 0) reachesC
decreases to 5 T. Figure 7(b) shows a typical
4.3 T and Bex
cross-section of the trapped field profiles for τ = 10 s. The
Bz (r ) profile changes from concave to convex with increasing
Bex and maintains a higher Bz value. It is noteworthy that theBz (r = 0) value is enhanced for the longer τ values.

Figures 8(a) and (b) show the time evolution of local fieldBz (t) and temperature T (t) at the centre of the bulk surface(α = 1.83 × 109 ) after applying a pulsed field of Bex = 8 Twith τ = 1 and 10 s, respectively. In both figures, the time tTP atwhich T (t)(r = 0) peaks is about 10 s, which is independentof the τ value because the thermal conductivity (κab , κc ) of
the bulk and that of the spacing plate (κcont ) are fixed. On theother hand, the time t BP , at which Bz (t)(r = 0) peaks, increases
concomitantly with increasing τ . In fact, t BP were, respectively
4 s and 15 s for τ = 1 and 10 s. For a longer pulse application,t BP increases and approaches tTP = 10 s. For τ = 1 s presented
in figure 8(a), Bz (t) decreases and saturates for t > 10 s,
at which T (t) decreases concomitantly with increasing time.
The results show that the flux creep was suppressed and thata large amount of the magnetic flux remained near the bulk
centre. For τ = 10 s presented in figure 8(b), t BP is nearly
equal to tTP ; their similar behaviour is visible. This scenario
is the main reason why the higher field was trapped for thelong magnetic pulse application. In this regard, the longpulse application is effective for trapping a higher magnetic
field. To realize a longer magnetic pulse experimentally, it is6－ 89 －

Supercond. Sci. Technol. 23 (2010) 105021

H Fujishiro and T Naito

Figure 8. Time dependence of the local field Bz (t)(r = 0) and temperature T (t)(r = 0) for a pulsed magnetic field of Bex = 8 T with(a) τ = 1 s and (b) τ =10 s at Ts = 40 K. Time dependences of the applied magnetic pulse Bex (t) are also shown as a dotted line.

(a)Figure 9. Time dependence of (a) the local field Bz (t)(r = 0) and (b) the temperature T (t)(r = 0) for a pulsed magnetic field of Bex = 9 Twith τ = 0.01 s for various thermal conductivities (κab , κc , κcont ) (α = 1.83 × 109 ). (c) Trapped field profiles for respective conditions.

necessary to use a condenser bank to store a large amount ofelectrical energy. However, using such a device is unrealistic
for practical applications at present because such condenser
banks are prohibitively expensive.

4.4. Effect of thermal conductivity enhancement on thetrapped field
As explained in section 4.3, a long pulsed field application
is a possible solution to realize a large Bz value. However,7－ 90 －

Supercond. Sci. Technol. 23 (2010) 105021

H Fujishiro and T Naito

it is difficult to prepare a large condenser bank for a longer
magnetic pulse. Using a simulation in which we can investigate
an unrealistic case, exploration was performed to enhance Bz
using a conventional condenser bank with τ = 0.01 s. To
enhance the Bz value, the time difference between t BP and tTP
should be minimized. In this subsection, the effects of thethermal conductivity enhancement of the bulk and the spacing
plate on the trapped field Bz are discussed.
Figures 9(a) and (b) respectively show the time evolutionof a local field Bz (t) and temperature T (t) for the bulk withvarious thermal conductivities of the bulk (κab , κc ) and thespacing plate (κcont ) after applying a pulsed field of Bex =9 T at 40 K. Figure 9(c) presents the trapped field profiles
for each condition. For a real condition with κab = 20,
κc = 4 and κcont = 0.5 W mK−1 , the trapped field profileis shown as concave. When κcont increases to 1000 times(κcont = 500 W mK−1 ), the trapped field does not change,
although the temperature increase was reduced for t > 10 s.
When the thermal conductivity increases to 100 times (κab =
2000, κc = 400 W mK−1 ), the generated heat diffuses overthe bulk. However, the trapped field is convex but remains
small because of the smaller heat transfer to the cold stage.
When the thermal conductivities of both the bulk and thespacing plate increase, trapped field enhancement is predictedbecause the time delay between Bz (t) and T (t) becomes small.
These results suggest that similar phenomena took place for
applying a pulsed field with τ = 0.01 s to those for the longpulse application (τ = 10 s). However, the enhancementof the thermal conductivity for the Ag-doped bulk is as low
as 10–20% [15] and enhancement of the contact thermal
conductivity, i.e. enhancement of κcont cannot be realized in
actual experimental set-ups.

intruding magnetic flux escapes by the flux creep becauseof the delayed temperature rise.
(3) A magnetic pulse application as long as τ = 1 or 10 s,
which enhanced the trapped field experimentally, reduces
the speed of the magnetic flux propagation. Then the
difference in the propagation speed between magnetic flux
and temperature becomes small. The results show that the
influence on the flux creep becomes slight and the trappedfield maintains a higher value. A long magnetic pulse
application during PFM is a possible solution to enhance
the trapped field.
(4) Based on analyses of long pulse application, we canenhance the trapped field for short pulse application
through enhancement of bulk thermal conductivity andcooling power, which are two or three orders of magnitude
higher than those of the real system. However, thatsimulation is unrealistic. Using numerical simulation, wemust explore another direction to enhance the trappedfield such as a multi-pulse technique for a bulk with an
inhomogeneous Jc distribution.

References[1] Yanagi Y, Itoh Y, Yoshikawa M, Oka T, Hosokawa T,
Ishihara H, Ikuta H and Mizutani U 2000 Advances inSuperconductivity vol 12 (Tokyo: Springer) p 470[2] Sander M, Sutter U, Koch R and Klaser M 2000 Supercond.
Sci. Technol. 13 841[3] Fujishiro H, Oka T, Yokoyama K, Kaneyama M andNoto K 2004 IEEE Trans. Appl. Supercond. 14 1054
[4] Fujishiro H, Hiyama T, Miura T, Naito T, Nariki S, Sakai N and
Hirabayashi I 2009 IEEE Trans. Appl. Supercond. 19 3545
[5] Fujishiro H, Hiyama T, Tateiwa T, Yanagi Y and Oka T 2007
Physica C 463–465 394[6] Fujishiro H, Kaneyama M, Tateiwa T and Oka T 2003 Japan. J.
Appl. Phys. 44 L1221[7] Fujishiro H, Tateiwa T, Fujiwara A, Oka T and Hayashi H 2006
Physica C 445–448 334[8] Kajikawa K, Yokoo R, Tomachi K, Enpuku K, Funaki K,
Hayashi H and Fujishiro H 2008 Physica C 468 1494
[9] Komi Y, Sekino M and Ohsaki H 2009 Physica C 469 1262
[10] Fujishiro H, Naito T, Furuta D and Kakehata K 2010 Physica C
470 1181[11] Fujishiro H, Kawaguchi S, Kaneyama M, Fujiwara A,
Tateiwa T and Oka T 2006 Supercond. Sci. Technol.
19 S540[12] Fujishiro H, Kaneyama M, Yokoyama K, Oka T and
Noto K 2005 Japan. J. Appl. Phys. 44 4919
[13] Kim Y B, Hempstead C F and Stand A R 1965 Phys. Rev.
139 A1163[14] Ishii Y, Shimoyama J, Ogino H and Kishio K 2009 J. Cryog.
Soc. Japan 44 573[15] Fujishiro H and Kohayashi S 2002 IEEE Trans. Appl.
Supercond. 12 1124

5. Summary
A theoretical simulation of electromagnetic and thermal fields
has been performed for a cryocooled superconducting bulk discwith homogeneous superconducting properties after applying amagnetic pulse. Important simulation results and conclusions
obtained from this study are summarized as follows.
(1) Simulation results for bulks with various critical current
densities Jc0 qualitatively reproduced experimental results
such as time and applied field dependences of the trappedfield Bz (t, r ) and the temperature rise T (t, r ) on the bulk
surface.
(2) For a rise time τ = 0.01 s of the magnetic pulse, which
is an ordinary experimental condition, the magnetic flux
propagation is about two orders of magnitude faster thanthe heat propagation at the bulk centre because of the
low thermal conductivity in the bulk. Consequently, the8－ 91 －

4. (A-41) H. Fujishiro, T. Naito, S. Ogawa, K. Nitta, J. Hejtmanek, K. Knizek and Z.
Jirak,“Valence shift of Pr ion from 3+ to 4+ in (Pr1-yYy)0.7Ca0.3CoO3 estimated by X-ray
absorption spectroscopy”,
J. Phys. Soc. Jpn. 81 (2012) 064709 (5 pages) (No. 189 paper)74－ 92 －

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Journal of the Physical Society of Japan 81 (2012) 064709
DOI: 10.1143/JPSJ.81.064709

Valence Shift of Pr Ion from 3+ to 4+ in (Pr1y Yy )0:7 Ca0:3 CoO3
Estimated by X-Ray Absorption Spectroscopy
Hiroyuki FUJISHIRO�, Tomoyuki NAITO, Satoru OGAWA, Naoki YOSHIDA,
Kiyofumi NITTA1 , Jiri HEJTMÁNEK2 , Karel KNÍŽEK2 , and Zdenek JIRÁK2
Faculty of Engineering, Iwate University, Morioka 020-8551, Japan
Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
2
Institute of Physics, ASCR, Cukrovarnická 10, 162 00 Prague 6, Czech Republic
1(Received January 12, 2012; accepted April 2, 2012; published online May 17, 2012)

The temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at the Pr L3 edge wasmeasured for the (Pr1�y Yy )0:7 Ca0:3 CoO3 samples (y ¼ 0:075 and 0.15), in which a peculiar metal–insulator (MI)transition and a spin-state (SS) transition took place simultaneously at a critical temperature TMI . The valence states ofpraseodymium ion were determined using the analyses of XANES spectra. The results suggest that the average valenceof the praseodymium ion increases below room temperature from the common value 3.0+, undergoes a steepestchange at TMI , and reaches ﬁnally 3.15+ and 3.27+ at 8 K for the y ¼ 0:075 and 0.15 samples, respectively. The ﬁnal
valences are consistent with those estimated by the entropy change using the Schottky peak due to the Pr4þ Kramers
doublet in the low-temperature speciﬁc heat shown in our previous paper [Phys. Rev. B 82 (2010) 165107].
KEYWORDS: Pr–Ca–Co–O, XANES, Pr valence shift, metal–insulator transition

1.

Introduction

The undoped perovskite cobaltites RECoO3 (RE: rareearth element and Y) show a temperature-induced spin-state
6 0eg )(SS) transition of Co3þ ions from a low spin state (LS; t2g
4 2eg ), followed by the formation
to a high spin state (HS; t2g
5 �� )of the metallic state of the intermediate spin state (IS; t2g
1)
at higher temperatures. The transition indicates a small
diﬀerence in the electronic energy �E between the crystalﬁeld splitting and Hund’s coupling energy.2,3) The doped
systems with a mixed Co3þ /Co4þ valence generally show astable metallic state, but a ﬁrst-order metal–insulator (MI)transition was observed on cooling some Pr-based cobaltites,
reported for the ﬁrst time in Pr0:5 Ca0:5 CoO3 at TMI ¼ 90 K
under ambient pressure by Tsubouchi and coworkers.4,5) The
electronic structure of this system was investigated byphotoemission spectroscopy soon after the ﬁrst report,
revealing that the electronic structure changes at TMI .6) The
mechanism of the transition was tentatively ascribed to a5 �
� to anspin-state crossover from itinerant cobalt states t2g3þ 6 0ordered mixture of localized LS Co (t2g eg , S ¼ 0) and LS
5 0
eg , S ¼ 1=2) states. Shortly thereafter, the existence
Co4þ (t2gof Co3þ /Co4þ ordering was questioned since the sametransition was evidenced in the less doped samples Pr1�x Cax CoO3 (x ¼ 0:3) under high pressures,7) or in (Pr1�y REy )1�x Cax CoO3 (0:2 � x � 0:5) with a partial substitution of Pr bysmaller RE cations or Y under ambient pressure.8,9) It has
been found that MI transition accompanied by SS transition isconditioned not only by the presence of praseodymium ions,but also by a suitable structural distortion that depends on the
average ionic radius and size mismatch of perovskite A-siteions.9) Furthermore, the critical temperature TMI changes
depending on the applied magnetic ﬁeld, so that TMI
decreases with increasing magnetic ﬁeld and the metallic
state is ﬁnally stabilized.10,11) The applied ﬁeld eﬀect is thus
opposite to the pressure dependence of TMI , where TMI
increases with increasing applied pressure.7)�E-mail: fujishiro@iwate-u.ac.jp

An alternative explanation has been proposed by Knı́žek
et al. on the basis of electronic-structure calculations andsome experimental data for Pr0:5 Ca0:5 CoO3 such as thesigniﬁcant lattice contraction and decrease in Pr–O bondlengths that accompany MI transition.12) It is suggested, intheir paper, that the formal cobalt valence changes below
TMI from mixed-valence Co3:5þ toward pure Co3þ withstrong preference for the LS state, and that the praseodymium valence increases simultaneously from Pr3þ towardPr4þ . The SS transition and formation of an insulating state
are thus an analogy of the compositional transition fromthe ferromagnetic metal La0:5 Sr0:5 CoO3 to the diamagnetic
insulator LaCoO3 .13,14)
The idea of praseodymium valence shift was experimentally conﬁrmed in a study of the transport, magnetic, andthermal properties of (Pr1�y Yy )0:7 Ca0:3 CoO3 (y ¼ 0{0:15)
by Hejtmánek et al.15) The crucial ﬁnding is the occurrenceof a Schottky peak at a low-temperature speciﬁc heat, which
results from a signiﬁcant population of Kramers Pr4þ ions.
Very recently, the valence transition of Pr has been probed in
Pr0:5 Ca0:5 CoO3 using Pr L3 and M4;5 edge X-ray absorption
spectroscopy (XAS) by Garcı́a-Munoz et al.16) They estimated that the valence of Pr ion shifted from 3.0+ to 3.15+
at 10 K. This seems to be a rather modest change in view of
the above-mentioned theoretical predictions and speciﬁcheat measurements in related (Pr1�y Yy )0:7 Ca0:3 CoO3 .
In this work, we applied a similar XAS spectroscopy tothe analysis of (Pr1�y Yy )0:7 Ca0:3 CoO3 (y ¼ 0:075 and 0.15),
the same samples as those used previously in the study of a
low-temperature speciﬁc heat.15) A detailed temperaturedependence of the XANES spectra around the Pr L3 edge
was measured using the bulk sensitive transmission method,and population of the Pr4þ state was derived from thespectra. In the calculation of average Pr valences, thedetected Pr4þ ions are taken as formally tetravalent,
although their electronic state is in fact a combination of
the ionic 4f 1 and oxygen-hole 4f 2 L conﬁgurations, making
the number of 4f electrons a non-integer. The Pr3þ ions are
essentially in an ionic 4f 2 electron conﬁguration.

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J. Phys. Soc. Jpn. 81 (2012) 064709

10

Experimental Procedure

3.1 Physical properties
The electrical resistivities and speciﬁc heats of the(Pr1�y Yy )0:7 Ca0:3 CoO3 samples for y ¼ 0:075 and 0.15 arepresented in Figs. 1 and 2. (More detailed physical properties of the samples are reported in ref. 15.) The y ¼ 0
sample, which is metallic over the entire temperature range,is also shown for comparison. For the Y-substituted samples,
the resistivity exhibits a sharp jump below the transition
temperatures of TMI ¼ 64 and 132 K for y ¼ 0:075 and 0.15,
respectively, and increases further with decreasing temperature, pointing to a localized character of the low-temperaturephase. Note that magnetic susceptibility drops markedly at
the same temperature, which is a strong sign that cobalt ionstransform to LS states below TMI .15) MI transition was
further manifested by a pronounced peak in the speciﬁc
heat, as shown in Fig. 2(a). The transitions in the resistivity
and speciﬁc heat of the y ¼ 0:075 sample are very sharp,
suggesting a ﬁrst-order character, while those for the
y ¼ 0:15 sample are much broader.
The low-temperature speciﬁc heat of the samples is shownin the Cp =T vs T plot in Fig. 2(b), in which the lattice andlinear electronic terms of Cp as well as the nuclear heat

(Pr1-yYy)0.7Ca0.3CoO3

Ωcm)
ρ (mΩ

y=0
y=0.075
y=0.15

107
10

5

10

3

T

MI

101
10

-1

0

50

100

150
T (K)

200

250

300

Fig. 1. (Color online) Temperature dependence of the electrical resistivity of (Pr1�y Yy )0:7 Ca0:3 CoO3 (y ¼ 0, 0.075 and 0.15).15)

120

(a)

T

MI

80

p

-1

-1

C (J mol K )10060(Pr1-yYy)0.7Ca0.3CoO340

y=0
y=0.075
y=0.15

20
0
0

50

100

150
T (K)

200

250

300

0.5

(b)
/T (J mol-1K-2)

Results and Discussion

11

109

schottky

Polycrystalline (Pr1�y Yy )0:7 Ca0:3 CoO3 (y ¼ 0, 0.075, and0.15) samples were prepared by a solid-state reaction. The
detailed sample preparation procedures were described
elsewhere.15) For the XANES measurements, some of thesamples were pulverized, mixed with 3N boron nitride(BN) powder with proper molar ratios in order to optimize
absorption, and pelletized to be 6 mm in diameter and
0.5 mm in thickness.
The Pr L3 -edge XANES spectra of the samples were
measured at BL01B1 of SPring-8 in Japan. The beam was
monochromatized using a Si(111) double-crystal monochromator. The spectra were recorded in the transmission modewith the detectors of the ionization chambers and obtained atvarious temperatures from 8 to 300 K using a cryocooler.
The valence of all the Pr ions was supposed to be 3.0+ forthe samples at 300 K. This is a justiﬁed assumption for
T � TMI , also supported by the oxygen stoichiometry of thepresent samples fabricated under the ambient pressure, incontrast to common problem of oxygen deﬁciency in the
prototypical Pr0:5 Ca0:5 CoO3 system.8) To determine themixed Pr3þ /Pr4þ content at low temperatures, a comparative
measurement of Pr6 O11 was carried out.
The recorded XANES spectra were modeled by the sumof three Lorentzian functions and one arctangent function
representing the step like edge of continuum excitations.
One Lorentzian function (peak A: 5966 eV) shows an
excitation from 2p3=2 to 4f 2 5d� , which represents Pr3þ ions.
The other Lorentzian functions (peak B2: 5969 eV andpeak B1: 5979 eV) show the excitations from 2p3=2 to
4f 2 L5d � and 4f 1 5d � , L being a ligand hole in the O 2p
orbital, both of which represent Pr4þ ions.17,18) The energy
diﬀerences between peaks A, B2, and B1 were ﬁxed
according to results of Hu et al.19) The curve ﬁttings were
performed in the energy range from 5944 to 5985 eV using
Athena software.20)
3.

H. FUJISHIRO et al.

0.4(Pr1-yYy)0.7Ca0.3CoO3

0.3

y=0
y=0.075
y=0.15

0.2
0.1

C

2.

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0
0

5

10
T (K)

15

20

Fig. 2. (Color online) (a) Temperature dependence of the speciﬁc heatof (Pr1�y Yy )0:7 Ca0:3 CoO3 (y ¼ 0, 0.075 and 0.15).15) (b) Low-temperature
speciﬁc heat shown in the CSchottky =T vs T plot. The lattice and linear
electronic terms for Cp , as well as the nuclear heat anomaly at low
temperatures, were subtracted. (The full line shows the ﬁt of the Schottky
peak for y ¼ 0:15.)

anomaly at low temperatures were subtracted. The anomalous peak observed for the y ¼ 0:075 and 0.15 samples isunderstood as a Schottky peak associated with the grounddoublet of Kramers ion Pr4þ , split by the internal magnetic
ﬁeld existing in the samples. On the other hand, for the y ¼ 0
sample, there is no Schottky peak in the range of 1–2 K,

064709-2－ 94 －#2012 The Physical Society of Japan

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normalized μ (E)(a) y=0.15

2

5974

5976

5978
5980
E (eV)

5982

5984

1
(Pr1-yYy)0.7Ca0.3CoO3
0

5950

5960

5970
5980
E (eV)

5990

6000

3

(b) y=0.075
8K
30K
64K
70K
76K
132K
300K

2

5974

5976

5978
5980
E (eV)

5982

5984

1
(Pr1-yYy)0.7Ca0.3CoO3
0

5950

5960

5970
5980
E (eV)

3

5990

6000

3.8

(c) Pr6O11
2

3.6

3.2
3
0.1

exp
fit

Pr 6O11

3.4

standard sample at 300K
y=0.075
y=0.15
0.2

0.3

0.4

0.5

I /I

0.6

0.7

0.8

B1 A

A

1

B2

B1
arctan

0

5950

5960

5970

5980

5990

6000

E (eV)
Fig. 3. (Color online) Temperature dependence of the XANES spectraat the Pr L3 -edge for the (a) y ¼ 0:15 and (b) 0.075 samples. The inset
of each ﬁgure shows the magniﬁcation of the spectra related to Pr4þ ions.
(c) XANES spectra for Pr6 O11 at 300 K, for which the ﬁtting were
performed (see text). The inset shows the calibration line for thedetermination of the valence of the Pr ion used in the study.

the intensity ratio of B1 to B2 was ﬁxed to be unity. The
valence of Pr ions for the samples in the course of
temperature was simply deduced from the intensity ratio
IB1 =IA of the B1 spectral peak to the A spectral peak22) using
the calibration line in the inset of Fig. 3(c). The validity ofthis procedure is based on the fact that the Pr3þ and Pr4þvalence states in Pr6 O11 are manifested in XANES spectraby single and double peaks, respectively (see also ref. 23),
which points to the same ionic 4f 2 and covalent 4f 1 =4f 2 L
conﬁgurations as those of the praseodymium ions in thepresent cobaltites.

064709-3－ 95 －

8K
90K
125K
132K
140K
200K
300K

Valence of Pr ion

3.2 XAS measurements
Figure 3(a) shows the temperature dependence of the
XANES spectra at the Pr L3 -edge for the y ¼ 0:15 sample.
The two main peaks situated at 5966 and 5979 eV (named
peaks A and B1) originate from the Pr 2p ! 5d transitions.
At 300 K, Pr3þ (4f 2 ) sites essentially contribute to thepeak A, with a little component at peak B1 caused
presumably by multiple scattering, which is commonly
introduced in the theoretical calculation of XANES.16) Whenthe temperature crosses the transition temperature TMI ¼
132 K, the shape of the XANES spectra changes markedly.
The intensity of peak B1 increases and, at the same time,the intensity of peak A decreases and a new component(peak B2 at 5969 eV) can be resolved on its high-energy
slope. The B1 and B2 peaks are manifestations of Pr4þstates, namely, of the conﬁgurations 4f 1 and 4f 2 L,
respectively.17–19) Similar behaviors are also observed forthe y ¼ 0:075 sample below TMI ¼ 64 K, as shown in
Fig. 3(b). These results suggest that the valence of the Pr
ions increases from 3+ toward 4+ below TMI , consistently
with what was reported for the Pr0:5 Ca0:5 CoO3 sample by
Garcı́a-Munoz et al.16) The temperature dependence of the
XANES spectra at the Pr L3 -edge was also measured for thePr0:7 Ca0:3 CoO3 sample (not shown), which was metallic
over the entire temperature range. There was no spectralchange down to 8 K, which suggested that the valence of the
Pr ion remained at 3.0+, as shown in the results of themetallic Pr0:55 Ca0:45 CoO3 sample.16)
In order to determine the valence shift quantitatively, the
XANES spectra were ﬁtted to a sum of three Lorentzianfunctions (peak A for Pr3þ and peaks B1 and B2 for Pr4þ )and one arctangent function representing the continuum
excitations, as indicated in x2. The Pr6 O11 spectrum shownin Fig. 3(c), in which no relevant spectroscopic changes
were detected at low temperatures, was regarded as astandard for Pr3:667þ . The spectra at 300 K for each of the(Pr1�y Yy )0:7 Ca0:3 CoO3 samples served as standards of
Pr3:0þ . In the ﬁtting of the temperature-dependent spectra,

H. FUJISHIRO et al.

3normalized μ (E)because all praseodymium ions remained in the Pr3þ valencewith a nonmagnetic singlet ground state.21) Instead, one may
notice a broad maximum in Fig. 2(b) with a center at about
17 K, which is a sign of a closely-lying exited singlet stateat an energy of about 4 meV. The total entropy change,
which was obtained by the integration of CSchottky =T overT , was determined to be 0.61 and 0.98 J K�1 mol�1 forthe y ¼ 0:075 and 0.15 samples, respectively. Considering
the theoretical R ln 2 ¼ 5:77 J K�1 mol�1 , the number ofKramers ions amounts to 0.12 and 0.17 Pr4þ per f.u., whichcorresponds to average valences of praseodymium, i.e.,
3.17+ and 3.29+ for the y ¼ 0:075 and 0.15 samples,
respectively.
It should be noted that the original interpretation of the
low-temperature Schottky peak in the (Pr1�y Yy )0:7 Ca0:3 CoO3 samples presumed a purely ionic state of Pr4þ ,particularly the free-ion multiplet 2 F5=2 split by a crystal
ﬁeld to Kramers doublets. The character of these states maychange signiﬁcantly in the covalent case, but the number ofPr4þ species determined in ref. 15 remains valid, since boththe ionic 4f 1 and oxygen-hole 4f 2 L states involve odd
number of electrons and display Kramers degeneracy.

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J. Phys. Soc. Jpn. 81 (2012) 064709

2.5

3.4
y=0.15

measuredarctanLorentz1 (A)Lorentz2 (B2)
Lorentz3 (B1)
simulation

T=8 K

1.5

(Pr1-yYy)0.7Ca0.3CoO3Valence of Pr ion

normalized μ (E)2.0

H. FUJISHIRO et al.

1.0

3.3 3.27+

y=0.075
y=0.15

TMI

3.2

3.15+

3.1

0.5
3.0
0

5950

5960

5970

5980

5990

0

6000

E (eV)

50

100

150
T (K)

200

250

300

Fig. 4. (Color online) Example of the ﬁtting of the XANES spectrum forthe y ¼ 0:15 sample at 8 K. For the ﬁtting, one arctangent function and three
Lorentzian functions are used (see text).

Fig. 5. (Color online) Temperature dependence of the valence of Pr ionsin the samples estimated using the XANES spectra and curve ﬁtting.

Figure 4 shows an example of the ﬁtting curve of the
XANES spectrum for the y ¼ 0:15 sample at 8 K, where thevalence change achieves a maximum. It is seen that the
XANES spectrum can be well ﬁtted within the energy range
including the related peaks of Pr3þ and Pr4þ . The B2component is also resolved and appears notable so thatthe resemblance with the Pr3þ /Pr4þ mixture in Pr6 O11 is
obvious. The temperature course is shown in Fig. 5. The
average valence changes gradually on cooling from 300 K,
with the steepest increase at TMI , and reaches ﬁnal values of
3.15+ and 3.27+ at 8 K for the y ¼ 0:075 and 0.15 samples,
respectively. The ambiguity of the estimated valence values
is �0:03, which results from the arbitrariness of theparameters in the arctangent and Lorentzian functions used.
We also deduced the average valence of Pr ions from theintensity ratio ðIB1 þ IB2 Þ=ðIA þ IB1 þ IB2 Þ of the B1, B2,
and A spectral peaks using another calibration line, in which
all the contributions of 4f 1 , 4f 2 , and 4f 2 L were considered tobe the same as those adopted by Yamaoka et al.17) Under
this condition, the average valences of Pr ions were 3.15+
and 3.31+ for the y ¼ 0:075 and 0.15 samples, which arenearly the same as that decided from the intensity ratio
IB1 =IA . Note that the estimated valences of the Pr ions are invery good agreement with that determined from the lowtemperature speciﬁc-heat experiments, i.e., 3.17+ and 3.29+
for the y ¼ 0:075 and 0.15 samples, respectively.15) The
gradual increase in the average valence of the Pr ions at
T > TMI on cooling from 300 K also suggests that thevalence of the Co ion must evolve from 3.3+ to a lower
value in order to maintain the charge neutrality. This means
that, with decreasing temperature, part of the LS-Co4þ
changes to IS-Co3þ still within the metallic phase, and thenthe IS-Co3þ states transform to LS-Co3þ below TMI . The
gradual charge transfer between the praseodymium andcobalt subsystem is in striking contrast to the abrupt (ﬁrstorder) character of the physical properties such as resistivity
and susceptibility, especially at y ¼ 0:075.
The valences of the Pr ions of 3.15+ and 3.27+ for the
y ¼ 0:075 and 0.15 samples, respectively, estimated fromthe intensity ratio IB1 =IA in XANES spectra, correspondto 0.097 and 0.161 Pr4þ per f.u. and is indicative of asigniﬁcant change in doping level in the cobalt subsystem(Co4þ content) in the low-temperature insulating state. For
y ¼ 0:075, the common valence distribution in the metallic
state (T � TMI ), i.e., (Pr0:925 3þ Y0:075 3þ )0:7 Ca0:3 2þ Co0:7 3þ Co0:3 4þ O3 2� , changes to (Pr0:786 3þ Pr0:139 4þ Y0:075 3þ )0:7 Ca0:3 2þ Co0:797 3þ Co0:203 4þ O3 2� (T � TMI ). For y ¼ 0:15,
the (Pr0:85 3þ Y0:15 3þ )0:7 Ca0:3 2þ Co0:7 3þ Co0:3 4þ O3 2� in themetallic state changes to (Pr0:620 3þ Pr0:230 4þ Y0:15 3þ )0:7 Ca0:3 2þ Co0:861 3þ Co0:139 4þ O3 2� in the low-temperature insulating state. The electron transfer between the praseodymium and cobalt subsystems thus acts as the driving force
for the stabilization of the LS-Co3þ states in the lowtemperature insulating state. Discussions of the relation
between the valence shift and the transition temperature TMI ,and of the eﬀect of the Ca ions on the transition are in
progress.
4.

Conclusion

The temperature dependence of the X-ray absorption nearedge spectra (XANES) at the Pr L3 -edge was measured fortwo (Pr1�y Yy )0:7 Ca0:3 CoO3 samples (y ¼ 0:075 and 0.15), in
which a peculiar metal–insulator (MI) transition and a spinstate (SS) transition took place simultaneously at criticaltemperatures TMI ¼ 64 and 132 K, respectively. The existence of two distinct praseodymium species was evidenced: the Pr3þ valence state of the ionic 4f 2 conﬁgurationand the formal Pr4þ valence state of highly covalentcharacter with admixed 4f 1 and oxygen-hole 4f 2 L conﬁgurations. The average valences of the praseodymium ion
were estimated by analyzing the XANES spectra. The
important experimental results and conclusions are summarized as follows.
(1) The room-temperature XANES experiment spectra
show a dominant single-peaked feature A (5966 eV),characteristic of the presence of the pure Pr3þ valence
state. On cooling across the transition temperature TMI , anincreasing population of Pr4þ states becomes evident fromthe fast increase in the intensity of peak B1 (5979 eV) in the
spectrum. At the same time, the intensity of peak A due toPr3þ decreases.
(2) The results obtained are indicative of a rather gradualcharge transfer between the praseodymium and cobalt sites
in the perovskite structure, which precedes the spin-state

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J. Phys. Soc. Jpn. 81 (2012) 064709

FULL PAPERS

transition of cobalt ions that occurs abruptly at a welldeﬁned TMI .
(3) Below TMI , the population of Pr4þ ions continues toincrease, reaching saturation at low temperatures. Using thequantitative analysis of the XANES spectra, the averagevalence of Pr ions at 8 K is determined to be 3.15+ and3.27+ for the y ¼ 0:075 and 0.15 samples, respectively.
These valences are in good agreement with those obtained
from the entropy change using the Schottky peak due to thePr4þ Kramers doublet in the low-temperature speciﬁc heat,i.e., 3.17+ and 3.29+.
Acknowledgments
The synchrotron radiation experiments were performedat the BL01B1 of SPring-8 with approval of Japan Synchrotron Radiation Research Institute (JASRI) (Proposal
No. 2011A1060). Part of the work was performed under the
ﬁnancial support of the Grant Agency of the Czech Republic
within the Project No. 204/11/0713.

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#2012 The Physical Society of Japan5. (A-48) Y. Noda, H. Fujishiro, T. Naito, A. Ito, T. Goto, J. Hejtmanek and Z. Jirak,“Electrical resistivity anomaly in (Pr1-yMy)1-xCaxCoO3 epitaxial films (M = Y, Gd)fabricated by pulsed laser deposition”,
AIP Advances 6 (2016) 025318 (9 pages) (No. 232 paper)75－ 98 －

AIP ADVANCES 6, 025318 (2016)

Electrical resistivity anomaly in (Pr1−yMy)1−xCaxCoO3
epitaxial films (M=Y, Gd) fabricated by pulsed
laser deposition
Y. Noda,1 H. Fujishiro,1,a T. Naito,1 A. Ito,2 T. Goto,2 J. Hejtmanek,3and Z. Jirak3
1

Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
3
Institute of Physics, ASCR, Cukrovarnicka 10, 162 00 Prague 6, Czech Republic
2(Received 27 November 2015; accepted 9 February 2016; published online 18 February 2016)(Pr1−yMy)1−xCaxCoO3 epitaxial films (M=Y, Gd) have been successfully fabricatedby pulsed laser deposition on the single crystal substrates with different lattice
constant. The polycrystalline bulk of this material shows a first-order metal-insulator(MI) transition below the critical temperature. Although ρ(T) of all the as-grownfilms shows a semiconducting behavior at entire temperature range, an anomalous ρ(T) upturn with wide hysteresis can be clearly seen for the film grown on
the SrLaAlO4 (SLAO) substrate, which applied the in-plane compressive stress tothe film. Such anomaly in ρ(T) is interpreted as a sign of the first-order phasetransition related with the spin-state (SS) transition, which was observed in thepolycrystalline bulk. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(http://creativecommons.org/licenses/by/4.0/). [http://dx.doi.org/10.1063/1.4942558]

I. INTRODUCTION

The perovskite cobaltites RECoO3 (RE=rare-earth element and Y) show a spin-state (SS) transition of Co3+ ions from a low spin state (LS; t 2g6eg0, S=0) to a high spin state (HS; t 2g4eg2, S=2)
with increasing temperature, followed by the formation of the metallic state of the intermediate
spin state (IS; t 2g5σ∗, S=1) at higher temperatures.1 The temperature induced SS transition indicates a small energy difference δE between the crystal-field splitting and Hund coupling energy.2,3The hole-doped systems such as La1−xSrxCoO3 generally show a temperature stable phase withitinerant cobalt states, which result presumably from the mixed IS Co3+/LS Co4+ or HS Co3+ /IS
Co4+ configurations, and undergo a ferromagnetic ordering at low temperatures. Most interestingly,
some Pr-based cobaltites exhibit a pronounced first-order transition to a low-temperature phaseof weakly paramagnetic character and reduced conduction. This effect was revealed for the firsttime on Pr0.5Ca0.5CoO3 at ∼ 90 K by the step-like resistivity jump and concomitant anomalies in
the magnetic susceptibility, heat capacity, lattice dilatation and photoemission spectroscopy.4–6 The
mechanism of the transition was tentatively ascribed to a spin state crossover from the itinerant
cobalt states to an ordered mixture of localized LS Co3+ and LS Co4+ (t 2g5eg0, S=1/2) states. Similar
metal-insulator (MI) transition was evidenced also in the less doped Pr1−xCaxCoO3 (x=0.3) underhigher hydrostatic pressures and in the (Pr1−xREy)1−xCaxCoO3 system (0.2<x<0.5) with a partial
substitution of Pr by smaller RE cations such as Sm, Eu, and Y under ambient pressure.7–9 This
peculiar transition appeared to be conditioned not only by the presence of both Pr and Ca ions, butalso by a larger structural distortion of the CoO6 network, depending on the average ionic radiusand size mismatch of perovskite A-site ions.9 Furthermore, the critical temperature TMI was founda corresponding author fujishiro@iwate-u.ac.jp

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6, 025318-1© Author(s) 2016.

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to decrease in a quadratic dependence of applied magnetic field, so that the transition could becompletely suppressed in very high fields.10
An alternative scenario explaining the nature of such specific transition was proposed on thebasis of electronic structure calculations exploiting the temperature dependence of the structuralexperimental data for Pr0.5Ca0.5CoO3,11 in which the formal cobalt valence should change below
TMI from mixed-valence Co3.5+ towards pure Co3.0+ with strong preference for the LS state and,concomitantly, the praseodymium valence should increase simultaneously from Pr3+ towards Pr4+.
The theoretical hypothesis about the crucial role of variable praseodymium valence was experimentally supported by the observations of a Schottky peak in the low temperature specific heatof (Pr1−yYy)0.7Ca0.3CoO3 ( y=0.075 and 0.15),12 and by the x-ray absorption near-edge structure(XANES) spectra at the Pr L 3 edge directly.13–16
It is widely desirable to use a single crystal or an epitaxial film for the physical investigation. In
the La1−xSrxCoO3 system, single crystals and thin films have been fabricated and investigated.17–19
In the epitaxial thin film, the electrical conduction and the spin state change depending on thefilm thickness and fabrication condition.19 However, for the (Pr1−yMy)1−xCaxCoO3 system withthe simultaneous MI and SS transition, only polycrystalline bulk materials have been investigatedexperimentally in the previous studies and there is no investigations using a single crystal or an
epitaxial film because of the difficulty of the fabrication.
When the material is prepared in the thin film form, the physical properties are sensitive to crystal structure, metallic composition, oxygen content etc, mainly depending on the lattice mismatch
between the substrate and the material. Thin films experience a stress due to mismatch of thelattice and the thermal expansion to the substrate, in addition to the intrinsic internal stress. In
particular, the interface between the film and the substrate can play an important role, giving rise
to boundary regions with different structures and affecting the transport and magnetic properties
due to the induced strain especially in very thin films. The strain in the epitaxial thin films canbe easily manipulated by the film thickness and the lattice parameter of the substrate material. For
example, in the RNiO3 thin film, which shows the bandwidth controlled MI transition, the transition
temperature, TMI, was increased (decreased) by tensile (compressive) in-plane strain.20 The strain
effect is attributed to an increase (decrease) of the Ni-O-Ni bond angle, which affects to films inthe same way as the bulk under higher pressure.21 Thin films of these materials have potential forvarious applications such as the use in resistive switches and phase-change memory.
In the present work, we fabricated the (Pr1−yMy)1−xCaxCoO3 epitaxial films (M=Y, Gd) bypulsed laser deposition (PLD) on the single crystal substrates with different lattice constant. We
investigated the electrical resistivity anomaly, which seemed to be related with the spin-state transition shown in the bulk materials.
II. EXPERIMENTAL PROCEDURE(Pr1−yYy)1−xCaxCoO3 (PYCCO) and (Pr1−yGdy)1−xCaxCoO3 (PGCCO) thin films were preparedby the PLD method using a fifth harmonic wave of YAG laser with λ=213 nm and a repetition
rate of 10 Hz. The pulse duration is 5 ns and the power is 18 mJ. (Pr0.8Y0.2)0.6Ca0.4CoO3 and(Pr0.7Gd0.3)0.6Ca0.4CoO3 polycrystalline targets with nominal composition were prepared by a standard solid-state reaction. Pr6O11, Y2O3, Gd2O3, CaCO3, Co3O4 raw powders with purity higher
than 99.9% were used as starting materials. The powders were mixed, calcined at 1000◦C for
12 h, pressed into pellets with a diameter of 20 mm and a thickness of 5 mm and then sintered at
1200◦C for 48 h in flowing oxygen gas. Powder X-ray diffraction analysis revealed that the sinteredtargets were a single phase. The target and the substrate were mounted in the vacuum chamber andwere rotated at the speed of 7 rpm and 3 rpm, respectively, to reduce non-uniform erosion and todeposit uniformly. The deposition was carried out for 1 - 4 hours in a pure oxygen atmosphereof 0.1 to 1.0 Torr and at a substrate temperature of 600◦C and the film thickness was measured
to be about 50∼100 nm. The films were grown on (001) oriented SrTiO3 (STO: a=0.3905 nm),
(LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT: a=0.3868 nm), LaAlO3 (LAO: a=0.3790 nm) and SrLaAlO4(SLAO: a=0.3756 nm, c=1.2636 nm) single crystal substrates. The pseudo cubic lattice parameterof the (Pr1−yYy)1−xCaxCoO3 bulk (x=0.4, y=0.2) is a=0.3775 nm and the lattice mismatch using

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FIG. 1. The relation between the lattice parameters of the (Pr0.8Y0.2)0.6Ca0.4CoO3 and those of the used single crystal
substrates.

the relation of ε=(aPYCCO-asub)/asub is +3.4% for STO, +2.5% for LSAT, +0.4% for LAO and -0.5%
for SLAO. The relation of the lattice parameters between the material and the substrates is shown in
Fig. 1, in which the in-plane tensile stress is applied to the film grown on the STO, LSAT and LAO
substrates and the in-plane compressive stress is applied in the film grown on the SLAO substrate. The
chemical composition of the grown films was measured by electron probe microanalysis (EPMA), in
which the measured composition of (x, y) of the film was decreased to (0.3, 0.13) from the nominal
composition of (0.4, 0.2) for the PYCCO sample. To clarify the crystalline quality of the grownfilms, X-ray diffraction analyses of θ-2θ and φ-2θ scans were performed, both of which identified theout-of-plane and in-plane alignments, respectively. The electrical resistivity ρ(T) was measured oncooling and heating runs in the 10 - 300 K range by a standard four-probe method for the as-grownfilms and heat-treated films under high-pressure oxygen gas (2.0 MPa) at 600◦C for 3 h.
III. RESULTS AND DISCUSSION

Figure 2 shows the out-of-plane XRD patterns (θ-2θ scan) of the PYCCO films fabricatedon the STO and SLAO substrates. The PYCCO films display clear (00l) reflections of the pseudo
cubic structure with no indications of impurities or miss-orientation together with the strong (00l)reflections from the substrates. These results demonstrate the out-of-plane orientation of PYCCO
thin films on the substrates.
Figure 3 presents the φ-2θ azimuth scan for the PYCCO film, fabricated on the SLAO substrate. Four sharp peaks of the (002) reflections were observed every 90 deg. and the in-planealignment can be confirmed, which were also confirmed for the films grown on the other substrates.
These results suggest that the PYCCO films are epitaxial films grown on the substrates.
Figure 4 shows the (002) intensity of the out-of-plane XRD patterns of the PYCCO films
on the STO substrate, as a function of the film thickness, d. The diffraction peak angle of thefilms decreases with increasing film thickness, d, and shifts toward the peak position for the bulk
crystal. These results suggest that the out-of-plane lattice constant of the epitaxial films on the STO
substrate is smaller than that of the bulk crystal and approaches the lattice constant of the bulk
material. This is because the tensile stress was induced in the film surface due to the positive latticemismatch ε (= +3.4%), and then was relaxed with increasing film thickness. On the other hand, forthe films grown on the SLAO substrate, the (002) peak was found at 2θ=47.70◦ for the d=100 nm
film (not shown), which was the lower angle than that of the bulk crystal (2θ=47.21◦). In this case,the in-plane compressive stress is induced in the film surface because of negative lattice mismatchε (= -0.5%).
Figure 5(a) shows the temperature dependence of the electrical resistivity, ρ(T), of the asgrown PYCCO films grown on the each substrate. The thickness of each film was about 50 nm.
ρ(T) of the target bulk is also shown in the figure, in which ρ(T) shows a jump with about twoorders of magnitude at TMI=140 K on the cooling run, and shows a sharp drop at TMI=150 K witha hysteresis. The absolute value of ρ(T) on the heating run was larger than that on the cooling

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FIG. 2. The out-of-plane XRD patterns (θ-2θ scan) of the PYCCO films grown on the (a) STO and (b) SLAO substrates in
the case of the target composition of (x=0.4, y=0.2).

run above TMI. The irreversibility in ρ(T) might come from the occurrence of micro cracks createdby the large volume contraction and expansion passing through the transition temperature.4 On theother hand, the ρ(T) curves for all the as-grown films show a semiconducting behavior without
pronounced anomaly, the absolute ρ(T) values change depending on the substrate used, and noirreversibility is detectable after the cooling and heating runs for the films grown on the STO, LSAT
and LAO substrates. Nonetheless, one may notice a distinct behavior of the film grown on the SLAO
substrate, namely the anomalous inflection point at 170 K and a wide hysteresis in ρ(T) below
this temperature that are seen in more detail Figure 5(b), where an alternative plot of logρvs.T −1/4,
commonly used for variable range hopping (VRH), is displayed. To understand this observation, we
refer to the fact that MI transition can be induced in polycrystalline Pr1−xCaxCoO3 (x=0.3) underhigh hydrostatic pressures and the critical temperature TMI increases with increasing pressure.7 The
compression stress in the present PYCCO film on SLAO substrate seems to have analogical effect toReuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. IP: 160.29.75.151 On: Fri, 19 Feb 2016 03:45:14－ 102 －

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FIG. 3. The in-plane XRD patterns (φ-2θ scan) of the PYCCO film fabricated on the SLAO substrate in the case of the target
composition of (x=0.4, y=0.2).

the hydrostatic pressure. In this sense, the anomalous ρ(T) upturn followed by a hysteresis region is
likely a sign of a similar first-order phase transition.
A question arises why the MI transition in the film grown on the SLAO substrate is lesspronounced compared to the bulk material. This is unexpected, especially in view of the fact that
actual mismatch conditions seem to be much in favor of the transition. Firstly, the out-of-planelattice constant of the film, 0.3820 nm, at room temperature (see Figure 6 below) combined with
the in-plane a=0.3756 nm imposed by SLAO substrate illustrates some deformation of the PYCCO
structure, but the unit cell volume remains exactly same as for bulk material. This is a signature that

FIG. 4. The (002) intensity in the out-of-plane XRD patterns of the PYCCO films, as a function of the thickness of the filmin the case of the target composition of (x=0.4, y=0.2).

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FIG. 5. Temperature dependence of the electrical resistivity, ρ(T ), at the cooling and heating runs: (a) The logρvs.T plot for
the as-grown (AG) PYCCO films on different substrates; (b) An alternative logρvs.T −1/4 plot with linear low-temperature
trend demonstrating the viability of the VRH scenario. The data shown by dashed lines refer to PYCCO films grown on LAO
and SLAO substrates, after a heat-treatment (HT) in high-pressure oxygen gas at 600◦C for 3 h.

film is likely well developed on the substrate without cracks. Secondly, it can be anticipated that theunit cell of PYCCO is shrank at the MI transition to the same extent as it is in the bulk material,
1.0% in volume or 0.3% in linear dimensions.22 Therefore, the deformation energy comprised in thefilm at room temperature will be removed below the transition to the low-temperature phase. There
should be evidently another reason for the less pronounced anomaly at TMI. It is worth mentioningthat early experiments on prototypical compound Pr0.5Ca0.5CoO3 revealed a critical sensitivity of
the MI transition to any oxygen deficiency. To check such hypothesis, the PYCCO films grownon the each substrate were post-annealed under high-pressure oxygen gas (2.0 MPa) at 600◦C for

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FIG. 6. The out-of-plane lattice constant a and the electrical resistivity for the PYCCO films at 300 K, ρ(300 K), of the
as-grown films on each substrate, as a function of lattice mismatch ε.

3 h. The resistivity data on two samples with minimum film/substrate mismatch were added to
the results on as-grown samples in Figures 5(a) and 5(b). For the film grown on the SLAO substrate, the anomalous ρ(T) upturn disappeared in the oxygenized sample and some irreversibility
in the cooling and heating runs arose. These changes suggest that, contrary to our expectation, thefirst-order phase transition vanished by the heat treatment. For the film grown on the LAO substrate,
the absolute ρ(T) value was only slightly increased by the post annealing.
Figure 6 presents the lattice constant a determined by out-of-plane measurements and theelectrical resistivity at 300 K, ρ(300 K), of the as-grown films on each substrate, as a function oflattice mismatch ε. The thickness of each film was about 50 nm. The out-of-plane lattice constanta monotonically decreases with increasing lattice mismatch ε, which suggests that the film was
extended in plane due to the tensile stress for the positive ε value. The ρ(300 K) value takes aminimum around ε=0, which is a reasonable trend. Namely, the deformation of CoO6 octahedra dueto the lattice mismatch affects the electron transport in the film.
Figures 7(a) and 7(b), respectively, show the temperature dependence of the electrical resistivity, ρ(T); the logρvs.T plot and the alternative logρvs.T −1/4 plot at the cooling and heating runs of
the as-grown (Pr1−yGdy)1−xCaxCoO3 (PGCCO) films on the each substrate. ρ(T) of the heat-treated
PGCCO films grown on the LAO and SLAO substrates are also shown. All the films, of which
the thickness was about 100 nm, were confirmed to be epitaxial films by XRD analysis. ρ(T) of
the target bulk is also shown in the figures, in which TMI was 70 K and 80 K on the cooling andheating runs, respectively. ρ(T) of all the as-grown films shows a semiconducting behavior at entire
temperature range. Similarly to the PYCCO film, an anomalous ρ(T) upturn with a wide hysteresis
can be clearly observed only for the as-grown film on the SLAO substrate, which is interpreted asa sign of the first-order phase transition. However, the ρ(T) upturn seems to remain after the heat
treatment as can be seen in Fig. 7(b). For the thinner PYCCO film on SLAO substrate about 50 nm
in thickness shown in Fig. 5, the transition was clearly suppressed by the heat treatment under thehigh-pressure oxygen gas, where the heat treatment removed the stress. On the other hand, in thepresent thicker PGCCO film on SLAO substrate with 100 nm in thickness, the heat treatment madeonly much smaller change. The appearance of the anomalous ρ(T) upturn and the relaxation after
the heat treatment change depending on the film thickness.

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025318-8

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AIP Advances 6, 025318 (2016)

FIG. 7. Temperature dependence of the electrical resistivity, ρ(T ), at the cooling and heating runs: (a) the logρvs.T plotand (b) the alternative logρvs.T −1/4 plot for the as-grown (AG) PGCCO films on different substrates. The data shown bydashed lines refer to the heat-treatment (HT) PGCCO films grown on LAO and SLAO substrates after the heat treatment inhigh-pressure oxygen gas at 600◦C for 3 h.

IV. SUMMARY

The (Pr1−yYy)1−xCaxCoO3 (PYCCO) and (Pr1−yGdy)1−xCaxCoO3 (PGCCO) films have been
fabricated by pulsed laser deposition (PLD) method on the single crystal substrates with different
lattice constants, and their crystallographic and electrical properties have been investigated. The
important experimental results and conclusions are summarized as follows.
(1) The obtained films have been confirmed to be epitaxial films grown on the single crystal
substrates with different lattice constants by XRD measurements.

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025318-9

Noda et al.

AIP Advances 6, 025318 (2016)(2) The electrical resistivity, ρ(T), of all the as-grown films shows a semiconducting behavior atentire temperature range. However, the anomalous ρ(T) upturn with a wide hysteresis can beclearly observed only for the films grown on the SLAO substrate, which applied the in-plane
compressive stress. The ρ(T) anomaly of the thin PYCCO film 50 nm in thickness on SLAO
vanished after the heat treatment in high-pressure oxygen gas. On the other hand, the ρ(T)upturn of the thick PGCCO film 100 nm in thickness on SLAO seems to remain after theheat treatment.
(3) The anomaly in ρ(T) is interpreted as a sign of the first-order phase transition accompaniedby the spin-state transition, which was observed in the polycrystalline bulk.
ACKNOWLEDGEMENTS

The authors thank Prof. N. Yoshimoto of Iwate University for his assistance in the in-plane
X-ray diffraction measurement. This work was partly supported by JSPS KAKENHI Grant No.
24540355 and was performed under the Inter-university Cooperative Research Program of theInstitute for Materials Research, Tohoku University.
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6. (H-1) K. Takahashi, H. Fujishiro and M. D. Ainslie,“A new concept of hybrid trapped field magnet lens (HTFML)”,
Supercond. Sci. Technol. 31 (2018) 044005 (9 pages) (No. 257 paper)76－ 108 －

Superconductor Science and Technology
Supercond. Sci. Technol. 31 (2018) 044005 (9pp)

https://doi.org/10.1088/1361-6668/aaae94

A new concept of a hybrid trapped ﬁeld
magnet lensKeita Takahashi1,3 , Hiroyuki Fujishiro1

and Mark D Ainslie2

1

Department of Physical Science and Materials Engineering, Faculty of Science and Engineering, Iwate
University, Morioka 020-8551, Japan2
Bulk Superconductivity Group, Department of Engineering, University of Cambridge, Cambridge CB2
1PZ, United Kingdom
E-mail: t2216017@iwate-u.ac.jp and fujishiro@iwate-u.ac.jp
Received 22 December 2017, revised 7 February 2018
Accepted for publication 12 February 2018
Published 7 March 2018
Abstract

In this paper, a new concept of a hybrid trapped ﬁeld magnet lens (HTFML) is proposed. The
HTMFL exploits the ‘vortex pinning effect’ of an outer superconducting bulk cylinder, which ismagnetized as a trapped ﬁeld magnet (TFM) using ﬁeld-cooled magnetization (FCM), and the‘diamagnetic shielding effect’ of an inner bulk magnetic lens to generate a concentrated magnetic
ﬁeld higher than the trapped ﬁeld from the TFM in the bore of the magnetic lens. This requires that,during the zero-ﬁeld-cooled magnetization process, the outer cylinder is in the normal state (T>superconducting transition temperature, Tc) and the inner lens is in the superconducting state(T<Tc) when the external magnetizing ﬁeld is applied, followed by cooling to an appropriate
operating temperature, then removing the external ﬁeld. This is explored for two potential cases: (1)exploiting the difference in Tc of two different bulk materials (‘case-1’), e.g. MgB2 (Tc=39 K) and
GdBaCuO (Tc=92 K) or (2) using the same material for the whole HTFML, e.g., GdBaCuO, bututilizing individually controlled cryostats, the same cryostat with different cooling loops or coolants,
or heaters that keep the outer bulk cylinder at a temperature above Tc to achieve the same desired
effect. The HTFML is veriﬁed using numerical simulations for ‘case-1’ using an MgB2 cylinder and
GdBaCuO lens pair and for ‘case-2’ using a GdBaCuO cylinder and GdBaCuO lens pair. As a result,the HTFML could reliably generate a concentrated magnetic ﬁeld Bc=4.73 T with the external
magnetizing ﬁeld Bapp=3 T in the ‘case-1’, and a higher Bc=13.49 T with higher Bapp=10 T in
the ‘case-2’, respectively. This could, for example, be used to enhance the magnetic ﬁeld in the boreof a bulk superconducting NMR/MRI system to improve its resolution.
Keywords: hybrid trapped ﬁeld magnet lens, bulk superconductors, trapped ﬁeld magnets,
magnetic lens, vortex pinning effect, diamagnetic shielding effect, ﬁnite element method(Some ﬁgures may appear in colour only in the online journal)
1. Introduction

introduction of strong pinning centers and the improvement ofcrystal growth techniques, which have resulted in increased critical current density, Jc [1, 2]. As a result, such bulks exhibit
higher trapped ﬁeld capabilities using ﬁeld-cooled magnetization(FCM) and have signiﬁcant potential for practical applications as
high-strength trapped ﬁeld magnets (TFMs) capable of generating
magnetic ﬁeld of several Tesla. Figure 1(a) shows the time
sequence of conventional FCM of superconducting bulks toutilize them as TFMs (the case shown is for a cylindrical ringbulk superconductor). Although the trapped ﬁeld, BT, of REBaCuO bulks, which can be estimated from the Jc(B, T)

The superconducting characteristics of REBaCuO bulks (RE: rareearth element or Y) continue to be enhanced due to the3Author to whom any correspondence should be addressed.

Content from this work may be used under the terms of theCreative Commons Attribution 3.0 licence. Any
further distribution of this work must maintain attribution to the author(s)and the title of the work, journal citation and DOI.
0953-2048/18/044005+09$33.00

1－ 109 －© 2018 IOP Publishing Ltd Printed in the UK

Supercond. Sci. Technol. 31 (2018) 044005

K Takahashi et al

Figure 1. Time sequence of (a) conventional magnetizing process of ﬁeld-cooled magnetization (FCM) of superconducting bulks to utilize them as
TFMs and (b) magnetizing process of zero-ﬁeld-cooled magnetization (ZFCM) for a conventional superconducting bulk magnetic lens.

the applied ﬁeld generated by the external magnetizing coil [6–9].
Figure 1(b) shows the time sequence of magnetizing process for aconventional bulk superconducting magnetic lens, for which zeroﬁeld-cooled magnetization (ZFCM) is used. The existence of slits
in the superconducting hollow cone is essential to suppress thecurrent along the circumferential direction and to concentrate themagnetic ﬂux. A concentrated ﬁeld of Bc=12.42 T has beenachieved at 20 K for a background ﬁeld of Bapp=8 T using abulk GdBaCuO magnetic lens [10] and Bc=30.4 T has beenachieved at the center of the lens in higher background ﬁeld of
Bapp=28.3 T elsewhere [11]. Using a bulk MgB2 magnetic lens,a concentrated ﬁeld of Bc=2.18 T at 4.2 K has also beenachieved for a background ﬁeld of Bapp=1 T [12]. Mechanicalreinforcement of the magnetic lens and the avoidance of the ﬂux
jump are necessary to achieve the magnetic lens effect stably [13].
Since the magnetic lens effect vanishes after the applied ﬁeld
decreased to zero, the external magnet must be operated continuously, which consumes a large amount of energy.
In this paper, we propose a new concept of a hybrid trapped
ﬁeld magnet lens (HTFML), consisting of a cylindrical bulk
TFM using the vortex pinning effect, combined with a bulk
magnetic lens using the diamagnetic shielding effect. The
HTFML can reliably generate a magnetic ﬁeld at the center of themagnetic lens higher than the trapped ﬁeld in the single cylindrical bulk TFM and the external magnetizing ﬁeld, even after thecharacteristics, could be over 20 T at 20 K in a bulk pair [3], themechanical strength of the brittle ceramic material restricts thepractical maximum trapped ﬁeld of such TFMs experimentally.
To date, REBaCuO disk bulks have been shown to trap magnetic
ﬁeld over 17 T by mechanical reinforcement using glass ﬁber
reinforced epoxy resin or shrink-ﬁt stainless steel to reduce theelectromagnetic hoop stress [3, 4]. Such TFMs, in which the ﬁeld
is trapped using the strong ‘vortex pinning effect’ of the material,
require a high, stationary magnetic ﬁeld to magnetize them andthey can trap ﬁelds nearly the same or slightly lower than theapplied ﬁeld, Bapp, using FCM, but such high ﬁelds are only
available from specialized magnets at a limited number of facilities worldwide. In this sense, such high-strength TFMs are notpractical for applications and much research has been carried out
on the pulsed ﬁeld magnetization (PFM) technique as a fast,compact and relatively inexpensive magnetization technique.
However, due to the large temperature rise associated with therapid dynamic movement of the magnetic ﬂux within the bulk,
the trapped ﬁeld capability is severely limited and only ﬁelds up
to around 5 T have been achieved using PFM [5].
On the other hand, a ‘magnetic lens’ using cone-shaped
superconducting bulks has been investigated, in which themagnetic ﬂux is concentrated in the bore of the magnetic lens
using the ‘diamagnetic shielding effect’ of superconducting
materials and the available magnetic ﬁeld in the lens is larger than2

－ 110 －

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Table 1. Numerical parameters for the Jc(B) characteristics of thebulk GdBaCuO material at 20 and 40 K using equation (2).

T (K)
40
20

Jc1 (A m−2)
9

3.5×10
9.0×109

BL (T)
0.9
1.5

Jc2 (A m−2)9

2.7×10
5.4×109

Bmax (T)

α

6.0
8.0

0.8
0.5

superconducting cylinder is made from bulk MgB2 and thesuperconducting magnetic lens is made from bulk GdBaCuO.
This model is abbreviated as ‘case-1’. The bulk MgB2
cylinder is 60 mm in outer diameter (O.D.), 40 mm in innerdiameter (I.D.) and 80 mm in height (H). The shape of themagnetic lens is referred from [13] so that the present numerical framework explains the concept of the HTFML basedon such a typical lens geometry (as shown in ﬁgure 2), but
importantly two slits exist that are 10° wide. The MgB2
cylinder and GdBaCuO lens are magnetized by a solenoid
coil of 170 mm in O.D., 120 mm in I.D. and 200 mm in H.
Another example is also provided, in which both the superconducting cylinder and magnetic lens are made from bulk
GdBaCuO, which is abbreviated as ‘case-2’. The numericalsimulation results for ‘case-1’ and ‘case-2’ are presented in
sections 4.1 and 4.2, respectively.
Electromagnetic phenomena during the magnetization
process are described by the fundamental equations shownelsewhere in detail [16–18]. The E–J power law is assumed todescribe the nonlinear electrical properties of the superconducting bulk:

Figure 2. Numerical model and dimensions of the MgB2 cylinder,
GdBaCuO magnetic lens and solenoid magnetizing coil for ‘case-1’.
The MgB2 cylinder is replaced by a GdBaCuO cylinder in ‘case-2’.

⎛ J ⎞nE = Ec ⎜ ⎟ ,⎝ Jc ⎠

externally applied ﬁeld decreases to zero. This concept requires
that, during the ZFCM process, the outer cylinder is in thenormal state (T> superconducting transition temperature, Tc) andthe inner lens is in the superconducting state (T<Tc) when theexternal magnetizing ﬁeld is applied, followed by cooling to an
appropriate operating temperature, then removing the externalﬁeld. This is explored for two potential cases: (1) exploiting thedifference in Tc of two different bulk materials (‘case-1’), e.g.
MgB2 (Tc=39 K) and GdBaCuO (Tc=92 K) or (2) using thesame material for the whole HTFML, e.g., GdBaCuO, but utilizing individually controlled cryostats, the same cryostat withdifferent cooling loops or coolants, or heaters that keep the outerbulk cylinder at a temperature above Tc to achieve the samedesired effect. The effectiveness and superiority of the HTFML is
veriﬁed using numerical simulations for two cases: ‘case-1’ using
an MgB2 cylinder and REBaCuO lens pair, and ‘case-2’ using a
REBaCuO cylinder and REBaCuO lens pair. The concentrated
magnetic ﬁeld in the HTFML changes depending on the superconducting characteristics of the bulks [14, 15], their shape andsize [12], as well as the magnetizing conditions.

(1)

where Ec (=10−4 V m−1) is the characteristic electric ﬁeld.
n=20 for the GdBaCuO bulk and n=100 for the MgB2
bulk are used [19]. The numerical simulation results depend
strongly on the Jc(B, T) characteristics of the superconductor[20–22]. For this study, the Jc(B) characteristics for the
GdBaCuO bulk are based on the equation presented by Jirsa
et al to represent the so-called ‘ﬁsh-tail’ or ‘peak’ effect foundin such superconducting materials [18, 23],
⎡1 ⎛
⎛ B⎞
⎛ B ⎞a ⎞ ⎤B
Jc (B) = Jc1 exp ⎜ - ⎟ + Jc2
exp ⎢ ⎜1 - ⎜⎟ ⎟ ⎥.
⎢⎣ a ⎝⎝ BL ⎠⎝ Bmax ⎠ ⎠ ⎥⎦
Bmax

(2 )

The values for the parameters Jc1, BL, Jc2, Bmax and α at
20 and 40 K used in the model are shown in table 1,
respectively.
The Jc(B) of the MgB2 bulk is described by the following
equation [24],⎡ ⎛ B ⎞b ⎤Jc (B) = Jc0 exp ⎢ - ⎜ ⎟ ⎥ ,⎢⎣ ⎝ B0 ⎠ ⎥⎦2. Numerical simulation framework(3 )where Jc0, B0 and β are ﬁtting parameters, which are summarized in table 2. Isothermal conditions are assumed while
ramping down the ﬁeld because the magnetization process is
slow; hence, no thermal model is included.

The following numerical simulation framework for the magnetizing process of the HTFML has been developed. A
schematic view of the three-dimensional numerical model andthe relevant dimensions are shown in ﬁgure 2, in which the3－ 111 －

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Table 2. Numerical parameters for the Jc(B) characteristics of thebulk MgB2 material at 20 K using equation (3).

T (K)
20

Jc0 (A m−2)
9

4.3×10

B0 (T)

α

1.1

1.5

the MgB2 cylinder is magnetized by FCM and magnetic
ﬂux is trapped in the cylinder. The magnetic ﬁeld
concentration effect slightly decreases due to thedecrease of external ﬁeld. However, a magnetic ﬁeld
at the center of the magnetic lens still remains due to theexistence of the trapped ﬁeld in the MgB2 cylinder.
(5) As a result, HTFML can reliably generate a magnetic
ﬁeld higher than BT of the single cylindrical TFM and
Bapp, even after Bex=0.
There are some examples of a practical cooling systemusing the difference in Tc of two superconducting components
for an aircraft motor design [25] and a magnetic levitation
application [26].
In ‘case-2’, in which both the superconducting cylinderand magnetic lens are made from bulk GdBaCuO, (1) and (2)above are changed as follows, labeled at (1’) and (2’):

Figure 3. Time step sequence of (a) the temperature, T and (b) theexternal ﬁeld, Bex, and concentrated magnetic ﬁeld, Bc, at the centerof magnetic lens for ‘case-1’, in which an MgB2 cylinder and
GdBaCuO magnetic lens are used. In ‘case-2’, the temperature of the
GdBaCuO lens follows the blue line and the GdBaCuO cylinder
follows the dotted orange line in the upper panel (see text).

(1’) The bulk GdBaCuO cylinder is maintained at 100 K(dotted orange line in ﬁgure 3) and the bulk GdBaCuO
magnetic lens is cooled to TH=40 K (blue line inﬁgure 3). Hence, the bulk GdBaCuO cylinder is in thenormal state and the bulk GdBaCuO lens is in the
superconducting state (step 0).
(2’) The external magnetic ﬁeld, Bex, is increased linearlyover ﬁve steps (steps 1–5) up to Bapp, and the magnetic
ﬁeld, essentially equal to Bapp, completely penetrates
the GdBaCuO cylinder, but the GdBaCuO lens ismagnetized by ZFCM.

3. Magnetizing procedure
First, the magnetizing process is described for the following
time step sequence, from (1) to (5), for the HTFML for ‘case1’, in which the bulk MgB2 cylinder and the bulk GdBaCuO
magnetic lens are used. Figure 3 shows the time sequence of(a) the temperature, T and (b) the external ﬁeld, Bex, andconcentrated magnetic ﬁeld, Bc, at the center of the magnetic
lens. The magnetizing applied ﬁeld, Bapp, corresponds to the
maximum value of Bex.

In the next section, the results of the numerical simulation for ‘case-1’ and ‘case-2’ are presented to prove theeffectiveness of the HTFML.

(1) The bulk MgB2 cylinder and the bulk GdBaCuO lens
are cooled from 100 K to TH=40 K, which is higher
than the superconducting transition temperature of
MgB2, Tc=39 K, but lower than that of GdBaCuO(Tc=92 K). In this stage, the MgB2 cylinder is in thenormal state and the GdBaCuO lens is in the superconducting state (step 0).
(2) The external magnetic ﬁeld, Bex, is ramped up linearly
at 0.222 T min−1 over ﬁve steps (steps 1–5) up to Bapp,
which corresponds to ZFCM of the GdBaCuO lens. The
magnetic ﬁeld, essentially higher than Bapp because of
the shielding effect by the magnetic lens, completely
penetrates the MgB2 cylinder and the magnetic ﬁeld isconcentrated at the center of the lens.
(3) The temperatures of both MgB2 cylinder and GdBaCuO
lens are then decreased to TL=20 K, which is lower
than the Tc of MgB2.
(4) Bex is decreased linearly at 0.222 T min−1 over ﬁve
steps (steps 6–10) down to zero. During this process,4. Simulation results and discussion
4.1. ‘Case-1’: MgB2 cylinder–GdBaCuO lensFigure 4 shows the time step dependence of the magnetic ﬁeld
proﬁle along the x-direction across the center of the lensduring (a) the ascending stage and (b) the descending stage of
ZFCM of the GdBaCuO lens under an applied ﬁeld,
Bapp=3 T in ‘case-1’, which incorporates FCM of the MgB2
cylinder. In ﬁgure 4(a), during the ascending stage from steps
0–5, the concentrated magnetic ﬁeld, Bc, at the center of the
GdBaCuO lens was enhanced with increasing Bex owing to
the diamagnetic shielding effect of the GdBaCuO lens. It canbe found that there is little or no ﬂux penetration in the
GdBaCuO lens region (r=±5∼18 mm) in this caseapplying a relatively low magnetic ﬁeld of 3 T by a magnetizing coil. The magnetic ﬂux intrudes into the lens from inner4－ 112 －

Supercond. Sci. Technol. 31 (2018) 044005

K Takahashi et al

Figure 4. Time step dependence of the magnetic ﬁeld proﬁle along
the x-direction across the center of the lens during (a) the ascending
stage and (b) the descending stage of ZFCM of the GdBaCuO lensunder an applied ﬁeld, Bapp=3 T in ‘case-1’, which incorporates
FCM of the MgB2 cylinder.

Figure 5. Time step dependence of the magnetic ﬁeld proﬁle along
the x-direction across the center of the lens during (a) the ascending
stage and (b) the descending stage of FCM of the MgB2 cylinder
without the GdBaCuO lens for an applied ﬁeld, Bapp=3 T at 20 K.

descending stages of FCM for an applied ﬁeld, Bapp=3 T for
only the MgB2 cylinder, without the GdBaCuO lens, in ‘case1’. In ﬁgure 5(a), when only the MgB2 cylinder is considered,the BT value is nearly the same as Bex in the ascending stage(steps 0–5), and attains a maximum value Bex=3 T at step 5
with a uniform magnetic ﬁeld proﬁle along x-direction, whichcorresponds to the applied ﬁeld proﬁle generated by theexternally magnetizing coil. During this ascending stage,
the MgB2 cylinder is in the normal state. In ﬁgure 5(b), in
the descending stage (steps 6–10), the trapped ﬁeld, BT, of the
MgB2 cylinder by FCM decreases slightly with decreasing
Bex, and settles to a ﬁnal value of BT=2.85 T at the ﬁnal step
(step 10) in the bore of MgB2 cylinder, now acting as a TFM
that can continue to provide the trapped ﬁeld quasi-permanently. One of the particular characteristics of the HTFML
device is to utilize the trapped ﬁeld from this TFM, instead ofrequiring a continuously applied ﬁeld from an external
magnetizing coil. Thus, it is useful to be able to reproduce amagnetic ﬁeld proﬁle similar to that which might be produced

periphery rather than outer edge because of the magnetic ﬂux
concentration, which will be discussed later for higher Bapp in‘case-2’. In this ascending stage, the GdBaCuO lens is under
ZFCM conditions at 40 K; however, the MgB2 cylinder is in
the normal state and is not yet utilized as a TFM. In
ﬁgure 4(b), during the descending stage of Bex from steps
5–10, which incorporates FCM of the MgB2 cylinder during
ZFCM of the GdBaCuO lens, Bc decreased with decreasing
Bex, but becomes stable after the external ﬁeld decreases tozero and a magnetic ﬁeld is trapped in the MgB2 cylinder. As
a result, Bc at the center of the GdBaCuO lens settled to
Bc=4.73 T at the ﬁnal step (step 10), which can be realized
quasi-permanently by the novel combination of the ‘vortex
pinning effect’ and ‘diamagnetic shielding effect’ of superconducting bulk materials.
Figures 5(a) and (b), respectively, show the time step
dependence of the magnetic ﬁeld proﬁles along the x-direction across the center of the lens during the ascending and5－ 113 －

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K Takahashi et al

Figure 7. Concentrated magnetic ﬁeld, Bc, at the center of themagnetic lens as a function of the external ﬁeld, Bex, for Bapp=3 T.
The trapped ﬁeld, BT, at the center of the MgB2 cylinder for the casewithout the GdBaCuO lens extracted from ﬁgure 5 is also shown.

as ﬁgure 4(a), in which Bc at the center of the GdBaCuO lenswas enhanced gradually with increasing Bex in the ascending
stage from steps 0–5. In ﬁgure 6(b), in the descending stage
from steps 6–10, it can be seen that there is some ﬂux
penetration into the inner edge of GdBaCuO lens at aroundr=±5∼7 mm from step 7 even for a relatively low appliedﬁeld of 3 T during ZFCM. The magnetic ﬁeld reachedeventually becomes −0.46 T at the center of the GdBaCuO
lens at the ﬁnal step (step 10) after ZFCM, resulting in a
reduction from the ideal of the GdBaCuO lens shielding effectin those regions where the magnetic ﬂux penetrates during
ZFCM. Thus, to maximize the lens’s shielding, and hence its
ability to concentrate the magnetic ﬁeld, the ﬂux penetration
should be minimized.
Figure 7 shows the concentrated magnetic ﬁeld, Bc, at thecenter of magnetic lens as a function of external ﬁeld, Bex, for
Bapp=3 T, which was extracted from ﬁgure 4. The trapped
ﬁeld, BT, at the center of the MgB2 cylinder was also
extracted from ﬁgure 5 for the case without the GdBaCuO
lens, which clariﬁes the effectiveness of the HTFML. For
only MgB2 cylinder, the BT value is nearly the same as Bex in
the ascending stage from step 0 and attains a maximum valueBex=3 T at step 5. The BT value is then 2.85 T at the ﬁnal
step (step 10) once Bex=0, showing that 3 T is a reasonablevalue to fully magnetize the MgB2 cylinder by FCM at 20 K.
In the case of the HTFML using both the MgB2 cylinder and
GdBaCuO lens, Bc at the center of the GdBaCuO lens wasenhanced up to 6.10 T at step 5 due to the shielding effect oflens and settled to Bc=4.73 T at the ﬁnal step (step 10),which is higher than both Bapp from the magnetizing coil andBT from the MgB2 TFM. These results indicate the superiorityof the proposed HTFML device, which can reliably generate
the concentrated magnetic ﬁeld higher than the applied ﬁeld
by the external magnetizing coil and the trapped ﬁeld of the
TFM, even after removal of the external ﬁeld.

Figure 6. Time step dependence of the magnetic ﬁeld proﬁle along
the x-direction across the center of the lens during (a) the ascending
stage and (b) the descending stage of ZFCM of the GdBaCuO lens
without the MgB2 cylinder for an applied ﬁeld, Bapp=3 T at 20 K.

by a magnetizing solenoid coil when we use the TFM as asource of magnetic ﬁeld for the HTFML, for further concentration of the magnetic ﬂux in the HTFML. This could, forexample, allow the realization of higher resolution in acompact and cryogen-free NMR/MRI system using annular
REBaCuO superconducting bulks [27, 28].
To achieve the highest concentrated ﬁeld in the lens, the
GdBaCuO magnetic lens must, in the ideal case, completely
shield the magnetic ﬁeld from its interior. However, since it isa type II superconductor, some magnetic ﬂux will penetrate
the material, depending on its Jc(B, T) characteristics (andhence operating temperature), as well as its geometry, during
the HTFML magnetizing procedure. Figures 6(a) and (b),respectively, show the time step dependence of the magnetic
ﬁeld proﬁles along the x-direction across the center of the lensduring the ascending and descending stages of ZFCM for an
applied ﬁeld, Bapp=3 T for the only GdBaCuO lens without
the MgB2 cylinder in ‘case-1’. Figure 6(a) is exactly the same6

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Figure 9. Time step dependence of the concentrated magnetic ﬁeld,
Bc, at the center of the GdBaCuO lens in the HTFML for Bapp=3, 6
and 10 T for ‘case-2’. The external ﬁeld, Bex, generated by thesolenoid magnetizing coil is also shown for each Bapp.

the GdBaCuO lens from steps 0–5 (noting that the MgB2
cylinder is in the normal state). In ﬁgure 8(a), the Bc value wasenhanced up to Bc=16 T at the center of the lens at step 5
when applying Bapp=10 T. The GdBaCuO lens could retain its
shielding effect even in a higher external magnetic ﬁeld of 10 T,
although the magnetic shielding effect weakens with increasing
applied ﬁeld due to further penetration of magnetic ﬂux [11]. In
ﬁgure 8(b), during the descending stage (steps 5–10), the
GdBaCuO cylinder maintains a trapped ﬁeld similar to Bapp at
the ﬁnal step (step 10) as it is magnetized by FCM, but below its
full capability based on its high Jc–B characteristics at 20 K. The
Bc value gradually decreased during the descending stage andsettled to a ﬁnal value of Bc=13.5 T at the center of the lens.
Figure 9 shows the time step dependence of the concentrated magnetic ﬁeld, Bc, and external ﬁeld, Bex, at the centerof the GdBaCuO lens for Bapp=3, 6 and 10 T for ‘case-2’.
Table 3 summarizes the concentrated magnetic ﬁeld, Bc, trapped ﬁeld from the TFM, BT, when only considering the TFM
cylinder (i.e., the lens is not present), at the central position at
the ﬁnal step (step 10), and the concentration ratio, Bc/Bapp, in‘case-2’ extracted from ﬁgure 9 for each actual Bapp. An
accurate value of Bapp is shown as B*app=3.09 T, 6.13 T and
10.18 T in this table, which was named roughly as Bapp=3, 6,
10 T so far. Similar results for ‘case-1’ from ﬁgure 4 are also
shown for comparison. For the lower Bapp=3 T, a magnetic
ﬁeld concentration ratio of Bc/Bapp=1.70 is achieved at theﬁnal step (step 10) in ‘case-2’, which is higher than 1.53 whenusing the MgB2 cylinder in ‘case-1’. This results from thehigher BT value of 3.09 T in ‘case-2’, where the outside
GdBaCuO cylinder was magnetized below its full capability.
Furthermore, in ‘case-2’, the concentration ratio decreased withincreasing Bapp from 1.70 for Bapp=3 T to 1.33 for
Bapp=10 T. In ﬁgure 9, the higher Bapp resulted in a larger ﬂux
creep during the descending stage of FCM of the TFM cylinderand further penetration of magnetic ﬂux in the ZFCM of the
GdBaCuO lens. There is a possibility to achieve further

Figure 8. Time step dependence of magnetic ﬁeld proﬁle along the x-

direction across the center of the lens during (a) the ascending stageand (b) the descending stage for Bapp=10 T in ‘case-2’.

4.2. ‘Case-2’: GdBaCuO cylinder–GdBaCuO lens

In the previous section, the superiority of the HTFML devicein ‘case-1’ using a MgB2 cylinder and REBaCuO lens pair
was veriﬁed, for which the concentrated magnetic ﬁeld wasenhanced up to Bc=4.73 T at the center of the GdBaCuO
lens, which is higher than the trapped ﬁeld of BT=2.8 T
generated by the MgB2 cylinder and the applied ﬁeld,
Bapp=3.0 T, generated by the external magnetizing coil. In
this section, the other example of ‘case-2’ using a REBaCuO
cylinder and REBaCuO lens pair for further concentration of
the trapped magnetic ﬂux is explored.
Figure 8 shows the time step dependence of the magnetic
ﬁeld proﬁle along the x-direction across the center of the lensduring (a) the ascending stage and (b) the descending stage for
Bapp=10 T in ‘case-2’. In this case, it should be noted that thetemperature of the GdBaCuO cylinder and lens must be controlled individually. Similar results were shown previously for‘case-1’ in ﬁgure 4(a), where the magnetic ﬁeld proﬁle wasshown during the ascending stage of ZFCM for Bapp=3 T for7－ 115 －

Supercond. Sci. Technol. 31 (2018) 044005

K Takahashi et al

Table 3. Concentrated magnetic ﬁeld, Bc, trapped ﬁeld by TFM, BT, at the center of the GdBaCuO lens at the ﬁnal step (step 10), andmagnetic ﬁeld concentration ratio, Bc/Bapp, in ‘case-2’ extracted from ﬁgure 9 for each actual applied ﬁeld, B*app. Similar results for ‘case-1’
from ﬁgure 4 are also shown for comparison.

‘case-1’ (MgB2 cylinder)‘case-2’ (GdBaCuO cylinder)

Bapp (T)B*app (T)BT (T)

Bc (T)

Bc/Bapp

3
3
6
10

3.09
3.09
6.13
10.18

2.85
3.09
6.13
10.18

4.73
5.25
9.19
13.49

1.53
1.70
1.50
1.33

comparatively inferior Jc(B) characteristics of MgB2 and it
must operate at a temperature lower than the superconducting
transition temperature of MgB2, Tc=39 K.
‘case-2’: The all-GdBaCuO HTFML offers higher concentrated ﬁelds at temperatures much higher than 39 K, butdoes require separate cooling of the cylinder and lens parts toobtain the necessary effect and it would weigh more.
This HTFML device could become a standard method fortrapped ﬁeld enhancement in several practical applications
using a superconducting bulk and there is a scope for optimization of the magnetic design, including geometry around twobulks, and magnetization conditions, including temperature andapplied ﬁeld. The effectiveness of the HTFML would beenhanced with improvements in the characteristics of thesuperconducting material(s) used, including the possibility ofutilizing new and improved materials such as BaFe2As2(Tc=38 K). The device could, for example, be used toenhance the magnetic ﬁeld in the bore of a bulk superconducting NMR/MRI system to improve its resolution.

enhancement of Bc and Bc/Bapp by optimization of the magnetic
design, including the geometry of the cylinder and lens, and themagnetization conditions, including temperature and appliedﬁeld. The shielding property of the magnetic lens should be also
exploited for further concentration of the trapped ﬁeld, such as
for hollow bulk cylinders [14]. These results show that theeffectiveness of the HTFML would be enhanced in terms of thecharacteristics of the superconducting material(s) used, including the possibility of utilizing new and improved materials,
such as BaFe2As2 (Tc=38 K) [29, 30].
5. Conclusion
A new concept of an HTFML, consisting of a superconducting
bulk cylinder TFM using the vortex pinning effect, combinedwith a bulk magnetic lens using the diamagnetic shielding effect,is proposed, which can reliably generate a magnetic ﬁeld at thecenter of the magnetic lens higher than the trapped ﬁeld by TFM
and the maximum external magnetizing ﬁeld, even after theexternally applied ﬁeld decreases to zero. The effectiveness andsuperiority of the HTFML was veriﬁed using numerical simulations for two examples: (1) an MgB2 cylinder and GdBaCuO
lens pair (‘case-1’) and (2) a GdBaCuO cylinder and GdBaCuO
lens pair (‘case-2’). In ‘case-1’, using the outer MgB2 cylinderand inner GdBaCuO lens pair, the MgB2 cylinder was magnetized by FCM with an applied ﬁeld, Bapp=3 T, during thedescending stage, also corresponding to ZFCM of the GdBaCuO lens. The trapped ﬁeld, BT=2.85 T, in the MgB2 TFM
cylinder was concentrated by the introduction of GdBaCuO lens,and a concentrated magnetic ﬁeld, Bc=4.73 T, was reliably
achieved at the center of the lens. In ‘case-2’, using the outer
GdBaCuO TFM cylinder and inner GdBaCuO lens pair, inwhich the GdBaCuO cylinder is held above Tc and the GdBaCuO lens is cooled below Tc for the ascending stage of magnetization, followed by both bulks being cooled below Tc for thedescending stage, a higher Bc=13.49 T, was reliably achievedat the center of the magnetic lens for Bapp=10 T.
The advantages and disadvantages of each HTFML,
comparing use of the MgB2 cylinder and the GdBaCuO
cylinder are summarized as follows:‘case-1’: The MgB2 HTFML only needs one coolingprocess for the whole device by exploiting the difference in Tc
of the two superconducting materials. Its weight would also
be lower due to the use of the lighter bulk MgB2 cylinder.
However, the trapped ﬁeld capability is limited in comparison
to the GdBaCuO cylinder (‘case-2’) because of the

Acknowledgments
This research is partially supported from JSPS KAKENHI
Grant No. 15K04646. Mark Ainslie would like to acknowledge ﬁnancial support from an Engineering and PhysicalSciences Research Council (EPSRC) Early Career Fellowship
EP/P020313/1. All data are provided in full in the results
section of this paper.

ORCID iDs
Keita Takahashi https://orcid.org/0000-0002-8278-2688
Hiroyuki Fujishiro https://orcid.org/0000-00031483-835X
Mark D Ainslie https://orcid.org/0000-0003-0466-3680

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7. (H-3) Sora Namba, Hiroyuki Fujishiro, Tomoyuki Naito, Mark D Ainslie andKeita Takahashi,“Experimental realization of a Hybrid Trapped Field Magnet Lens (HTFML)
using a GdBaCuO magnetic lens and MgB2 bulk cylinder”,
Supercond. Sci. Technol. Letter 32 (2019) 12LT03 (7 pages) (No. 271 paper)77－ 118 －

Superconductor Science and Technology
Supercond. Sci. Technol. 32 (2019) 12LT03 (7pp)

https://doi.org/10.1088/1361-6668/ab5048

LetterExperimental realization of a hybrid trapped
ﬁeld magnet lens using a GdBaCuO
magnetic lens and MgB2 bulk cylinder
Sora Namba1,3 , Hiroyuki Fujishiro1 , Tomoyuki Naito1 ,Mark D Ainslie2 and Keita Takahashi1
1Department of Physical Science and Materials Engineering, Faculty of Science and Engineering, Iwate
University, 4-3-5 Ueda, Morioka 020-8551, Japan2
Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United
KingdomE-mail: g0318128@iwate-u.ac.jp
Received 13 August 2019, revised 13 October 2019
Accepted for publication 18 October 2019
Published 5 November 2019
Abstract

A hybrid trapped ﬁeld magnet lens (HTFML) is a promising device that is able to concentrate amagnetic ﬁeld higher than the applied ﬁeld continuously, even after removing an external ﬁeld,
which was conceptually proposed by the authors in 2018. This paper presents, for the ﬁrst time,the experimental realization of the HTFML using a GdBaCuO magnetic lens and MgB2 trapped
ﬁeld magnet cylinder. A maximum concentrated magnetic ﬁeld of Bc=3.55 T was achieved at
the central bore of the HTFML after removing an applied ﬁeld of Bapp=2.0 T at T=20 K. For
higher Bapp, the Bc value was not enhanced because of a weakened lens effect due to magnetic
ﬂux penetration into the bulk GdBaCuO material comprising the lens. The enhancement of thetrapped ﬁeld using such an HTFML for the present experimental setup is discussed in detail.
Keywords: hybrid trapped magnet ﬁeld lens, bulk superconductors, trapped ﬁeld magnets,
magnetic lens, vortex pinning effect, magnetic shielding effect(Some ﬁgures may appear in colour only in the online journal)
1. Introduction

trapped by the strong ‘vortex pinning effect’, are usuallymagnetized by ﬁeld-cooled magnetization (FCM) using ahigh, stationary magnetic ﬁeld, for which a magnetic ﬁeld
nearly the same or slightly lower than the applied ﬁeld can betrapped. The trapped ﬁeld capability of such bulks, as estimated from state-of-the-art Jc(B, T) characteristics could
exceed 20 T at 20 K in a disk bulk pair [4]. However, thetrapped ﬁeld is limited experimentally by the poor mechanicalstrength of the brittle ceramic material [5]. A large Lorentz
force is developed in the bulk during the magnetization process, which sometimes results in crack formation and propagation, leading to eventual mechanical failure [6, 7]. To
date, REBaCuO disk bulks have trapped magnetic ﬁelds over
17 T by mechanical reinforcement using glass ﬁber reinforced
epoxy resin or shrink-ﬁt stainless steel to reduce theTrapped ﬁeld magnets (TFMs) using superconducting bulks
such as REBaCuO (RE: a rare earth element or Y) and MgB2
have been vigorously investigated for various practicalapplications; for example, rotating machines, magnetic
separation, ﬂywheel energy storage systems and so on [1–3].
Superconducting bulk TFMs, in which magnetic ﬂux is3

Author to whom any correspondence should be addressed

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Supercond. Sci. Technol. 32 (2019) 12LT03

Figure 1. (a) Cross-sectional view of the schematic illustration of the experimental setup for the HTFML on the cold stage of a refrigerator.

(b) Cross-sectional and top views of the GdBaCuO magnetic lens with slits. When a magnetic ﬁeld is applied along the +z-axis direction to
the GdBaCuO magnetic lens, the magnetic ﬁeld penetrates from the slits and the shielding current ﬂows as shown by the red arrows. As aresult, the magnetic ﬁeld increases along the +z-direction due to the shielding current.

electromagnetic hoop stress [4, 8]. A ring-shaped bulk
superconductor that can produce uniform, high magnetic
ﬁelds within the central bore is a strong candidate for compact
cryogen-free nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems [9–11]. The 1H spectraof toluene with a full width at half maximum of 0.4 ppm(80 Hz) was achieved in the 10 mm room temperature bore in
the bulk NMR [10]. The ﬁrst MRIs using annular EuBaCuO
bulks were also reported with a magnetic homogeneity of
37 ppm (peak-to-peak) achieved in a Φ 6.2 mm×9.1 mm
cylindrical space with ﬁrst order shimming [11]. Using thissystem, a clear 3D image of a chemically-ﬁxed mouse fetus
was acquired.
On the other hand, a ‘magnetic lens’ using cone-shaped
superconducting bulks has been investigated, in which amagnetic ﬁeld is concentrated in the bore of the lens using the‘diamagnetic shielding effect’ of superconducting materials
and the available magnetic ﬁeld in the lens is higher than theapplied ﬁeld generated by an external magnetizing coil
[12–18]. For example, a concentrated ﬁeld of Bc=12.42 T
has been achieved at 20 K for a background ﬁeld of
Bapp=8 T using a bulk GdBaCuO magnetic lens [12]. Since
the magnetic lens effect vanishes after the applied ﬁeld
decreased to zero, the external magnet must be operated
continuously, which consumes energy and is not environmentally friendly.
We recently proposed a new concept of a hybrid trapped
ﬁeld magnet lens (HTFML) [19], consisting of a cylindricalbulk TFM exploiting the ‘vortex pinning effect’, combinedwith a bulk magnetic lens exploiting the ‘diamagnetic
shielding effect’. Using numerical simulations, the HTFML
was shown to be able to reliably generate a magnetic ﬁeld in
the central bore of the magnetic lens that is higher than boththe trapped ﬁeld in the single cylindrical bulk TFM and theexternal magnetizing ﬁeld, even after the externally appliedﬁeld decreases to zero. For a REBaCuO magnetic lens and
MgB2 TFM cylinder, the HTFML could reliably generate aconcentrated magnetic ﬁeld of Bc=4.73 T with an external
magnetizing ﬁeld Bapp=3 T. For an HTFML comprised of
REBaCuO bulks for both magnetic lens and TFM cylinder, aconcentrated magnetic ﬁeld of Bc=13.49 T could be generated with an external magnetizing ﬁeld Bapp=10 T, where
the temperature of both parts is controlled independently [19].
In addition, the shape of the magnetic lens in the HTFML has
been optimized, and the mechanical stress in the cylinder andlens parts has also been estimated during the magnetizing
process [20].
In this paper, we present, for the ﬁrst time, the experimental realization of the HTFML using a GdBaCuO magnetic lens and MgB2 TFM cylinder, based on the samemagnetizing procedure proposed in [19]. The experimental
results are compared with the simulated ones and enhancement of the Bc value in HTFML is discussed in detail.

2. Experimental procedure
2.1. Experimental setup

Figure 1(a) shows the schematic cross-section of the experimental setup of the HTFML on the cold stage of a refrigerator. The MgB2 cylindrical bulk (60 mm in outer diameter(OD), 40 mm in inner diameter (ID), and 60 mm in height(H)) was fabricated using the inﬁltration method by Experiments Projects Constructions S. R. I., Italy [21, 22].
Figure 1(b) shows the cross-section and top view of the
GdBaCuO magnetic lens. The GdBaCuO magnetic lens was
prepared by the following process: stacked GdBaCuO
cylindrical bulks (OD=36 mm, ID=10 mm, H=30 mm),fabricated using the QMG™ method by Nippon Steel Corporation, Japan [23, 24], were machined into a cone-shape of
OD=30 mm, ID=10 mm, ID2=26 mm, outer height(OH)=30 mm and inner height (IH)=8.0 mm, as shown inﬁgure 1(b). The dimensions of the bulk magnetic lens were2

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Supercond. Sci. Technol. 32 (2019) 12LT03

optimized using numerical simulations [20]. Thin slits ofwidth 200 μm was made to disrupt the circumferential ﬂow of
the shielding current during the zero-ﬁeld-cooling (ZFC)
process, which plays an important role in magnetic ﬂux
concentration for the magnetic lens [19]. When an external
magnetic ﬁeld is applied along the +z-axis direction to the
GdBaCuO magnetic lens, the same magnetic ﬁeld penetrates
into the central bore from the slits. The shielding current
ﬂows as shown by the red arrows in ﬁgure 1(b) and an
additional magnetic ﬁeld exists along the +z-axis direction,
mainly due to the counterclockwise shielding current nearest
to the central bore. As a result, the magnetic ﬁeld is enhanced
along the +z-axis direction, which is then higher than theapplied ﬁeld.
The GdBaCuO magnetic lens was encapsulated in astainless steel (SS) holder to prevent fracture of the bulk due
to the large Lorentz force during the magnetization process,and was connected thermally to the cold stage of the refrigerator. The MgB2 cylindrical bulk was reinforced by a SS
cylinder (ID=60 mm, OD=66 mm and H=60 mm) andthe top SS plate (ID=36 mm, OD=66 mm andH=3 mm), which were effective in preventing mechanicalfracture [25, 26]. These SS holders apply a compressive stressto the bulk cylinder and bulk lens during the cooling processfrom room temperature to the operating temperature (e.g.
20 K) due to the difference in the coefﬁcient of thermal
expansion between SS and the bulk superconducting materials. Two CERNOX™ thermometers were attached for monitoring the temperature of the HTFML; one was mounted
directly on the top surface of the MgB2 cylinder, and the otherwas placed on the top surface of the SS holder of the
GdBaCuO lens. Thin indium sheets were inserted between thebulks and the cold stage of the refrigerator (or SS holder) toobtain good thermal contact. The temperature of the cold
stage was controlled using a Pt-Co thermometer and a resistive heater, attached to bottom surface of the cold stage. The
concentrated ﬁeld, Bc, was measured in the central bore of the
HTFML by an axial-type Hall sensor (F W Bell, BHA-921).
The HTFML device was placed in a vacuum chamber andthen evacuated by a vacuum pump system.

Figure 2. Time step (TS) sequence of the external ﬁeld (black: left

vertical axis), Bex, at the center of the HTFML and the operating
temperature (red: right vertical axis), T, during the magnetizing
process to realize the HTFML. The magnetizing applied ﬁeld, Bapp,corresponds to the maximum value of Bex.

(1) The external magnetic ﬁeld, Bex, was ramped up
linearly at +0.222 T min−1 to Bapp=1−3 T over ﬁve
steps, where TS of the ascending stage is deﬁned asTS=1–5. This process corresponds to ZFC magnetization of the GdBaCuO lens, in which the magnetic
ﬁeld at the center is essentially higher than Bapp becauseof the shielding effect by the magnetic lens.
(2) The temperatures of both the MgB2 cylinder and
GdBaCuO lens were decreased to T=20 K under theapplied ﬁeld Bapp, with both materials now in the
superconducting state.
(3) Bex was decreased linearly at −0.011 T min−1 over ﬁve
steps (TS=6–10) down to zero. During this process,the MgB2 cylinder was magnetized by FCM andmagnetic ﬂux was trapped in the cylinder. A magnetic
ﬁeld at the center of the magnetic lens still remains dueto the existence of the trapped ﬁeld in the MgB2
cylinder. As a result, the HTFML can reliably generatea magnetic ﬁeld higher than the trapped ﬁeld in the
single MgB2 TFM cylinder and Bapp, even after
Bex=0.
Prior to the HTFML experiments, the trapped ﬁeld
properties of the MgB2 cylinder and the magnetic concentration capability of the GdBaCuO lens were investigatedindependently using the same time sequence as shown inﬁgure 2 under the external magnetic ﬁeld of Bapp=1−3 T, inwhich either the MgB2 cylinder or GdBaCuO lens was set on
the cold stage.

2.2. Magnetization procedure

Figure 2 shows the time sequence of the external ﬁeld (leftvertical axis), Bex, at the center of the HTFML and theoperating temperature (right vertical axis), T, during themagnetizing process of the HTFML. The magnetizing external ﬁeld, Bapp, corresponds to the maximum value of Bex. The
HTFML device set in the vacuum chamber was inserted into a
cryocooled 10 T superconducting solenoid magnet (JASTEC
JMTD-10T100). First, the MgB2 bulk cylinder and GdBaCuO
bulk lens were cooled to T=40 K. In this stage, the MgB2
cylinder is in the normal state and the GdBaCuO lens is in the
superconducting state, where the time step (TS) is deﬁned asTS=0. The proof-of-concept experiments of the HTFML
were performed according to the following magnetizing
process.

3. Results and discussion
3.1. Trapped field capability of the single MgB2 cylinder

To conﬁrm the trapped ﬁeld capability of MgB2 cylinder, thetrapped ﬁeld properties of the single MgB2 cylinder wasmeasured. Figure 3(a) shows the time evolution of theexternal ﬁeld, Bex, and trapped ﬁeld, Bc, at the center of thesingle MgB2 cylinder during the same time sequence shown3－ 121 －

Supercond. Sci. Technol. 32 (2019) 12LT03

Figure 4. Time step (TS) dependence of the measured magnetic ﬁeld,

Bc, at the center of the single MgB2 cylinder during themagnetization process for applied ﬁelds Bapp=1.0–3.0 T.

Figure 3. Time evolution of (a) the measured magnetic ﬁeld, Bc, atthe center of the single MgB2 cylinder and external ﬁeld, Bex, and (b)the temperatures of MgB2 cylinder and cold stage during themagnetization process for an applied ﬁeld of Bapp=2.0 T.

in ﬁgure 2 under an external magnetic ﬁeld of Bapp=2.0 T.
Figure 3(b) shows the time evolution of the temperatures of
the cold stage and the MgB2 cylinder for the same process. In
the ascending stage, the magnetic ﬁeld, Bc, increased linearlywith increasing Bex and the magnitude of Bc was the same as
the external ﬁeld (Bc=Bex=2.0 T) because the MgB2
cylinder was in normal state (T=40 K). In the descending
stage, after cooling to 20 K, the Bex was slowly decreased at aconstant rate of −0.011 T min−1 and the FCM process was
performed for the MgB2 cylinder. As a result, a trapped ﬁeld
remained of Bc=2.0 T after Bex was decreased to zero due tothe conventional vortex pinning effect. In ﬁgure 3(b), thetemperature of the MgB2 cylinder was nearly the same as thatof the cold stage because of the good thermal contact.
Figure 4 shows the TS dependence of the trapped ﬁeld,
Bc, at the center of the single MgB2 cylinder under external
magnetic ﬁelds of Bapp=1−3 T. In the ascending stage fromTS=0 to 5, the magnetic ﬁeld increases linearly withincreasing TS and the magnitude is the same as the externalﬁeld because the MgB2 cylinder is in normal state. In thedescending stage of the FCM process, for the applied ﬁelds ofBapp=1.0 and 2.0 T, trapped ﬁelds of 1.00 T and 1.98 T,
respectively, were achieved at TS=10 without ﬂux creep.
On the other hand, for higher applied ﬁelds of 2.5 and 3.0 T,
the TS dependence of Bc after TS=5 gradually decreased
and the ﬁnal trapped ﬁeld was 2.18 T, which suggests the
maximum trapped ﬁeld capability of the MgB2 cylinder atT=20 K. The trapped ﬁeld cannot increase over 2.18 T, even
if applied ﬁeld is higher than 3.0 T. In the conceptual paper[19], Bc=2.85 T was predicted at the ﬁnal step at T=20 K
in the bore of MgB2 cylinder for Bapp=3.09 T. The lower Bc

Figure 5. Time evolution of (a) the measured magnetic ﬁeld, Bc, atthe center of the single GdBaCuO bulk lens and external ﬁeld, Bex,and (b) the temperatures of GdBaCuO bulk lens and cold stage
during the magnetization process for an applied ﬁeld of
Bapp=2.0 T.

value in the present experiment results from the lower Jc(B, T)of the present MgB2 cylinder, compared with that used in thesimulations in [19].
3.2. Magnetic shielding capability of the single GdBaCuO
bulk lens

The magnetic shielding capability of the GdBaCuO bulk lens
was measured using the single GdBaCuO bulk lens during theZFC process. Figure 5(a) shows the time evolution of themagnetic ﬁeld, Bc, at the center of the single GdBaCuO bulk
4

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Supercond. Sci. Technol. 32 (2019) 12LT03

Figure 6. TS dependence of the measured magnetic ﬁeld, Bc, at thecenter of the single GdBaCuO magnetic lens during the magnetization process under applied ﬁelds, Bapp=1.0–3.0 T. For TS=10,
the Bc value increased negatively with increasing Bapp.

Figure 7. Time evolution of (a) the measured magnetic ﬁeld, Bc, atthe center of the HTFML and external ﬁeld, Bex, and (b) thetemperatures for each measurement point during the magnetizing
process for Bapp=2.0 T.

lens and the external ﬁeld, Bex, during the same time sequence
shown in ﬁgure 2, under an external magnetic ﬁeld of
Bapp=2.0 T. Figure 5(b) shows the time evolution of thetemperatures of GdBaCuO bulk lens and the cold stage under
the same process. In the ascending stage, a clear magnetic
ﬁeld concentration was observed; Bc=3.76 T was achieved,
which resulted in a magnetic ﬁeld concentration ratio of
Bc/Bapp=1.88. A temperature rise of about 2.1 K took place
during ascending stage from 0 to 10 min, originating frommagnetic ﬂux penetration into the magnetic lens. When thetemperature of the cold stage was set to 20 K, the minimum
temperature of the GdBaCuO bulk lens encapsulated by the
SS holder was only 26.5 K, which may come from animperfect thermal contact between the bulk lens and the SS
holder. It should be noted that the ﬁnal Bc value was not zero,
but a negative one of −0.48 T. This result suggests that somemagnetic ﬂux penetrated into the surface of the bulk lens anda residual magnetic ﬁeld along the –z-direction existed due tothe vortex pinning effect.
Figure 6 shows the TS dependence of the magnetic ﬁeld,
Bc, at the center of the single GdBaCuO bulk lens during theZFC process under applied magnetic ﬁelds ofBapp=1.0−3.0 T. In the ascending stage from TS=0 to 5,
the magnetic ﬁeld was concentrated by the shielding current.
For lower Bapp=1 and 2 T, Bc=2.04 and 3.76 wereachieved at TS=5, which correspond to magnetic ﬁeld
concentration ratios, Bc/Bapp, of 2.04 and 1.88, respectively.
The Bc values increased for higher Bapp, which were 4.55 T
and 5.19 T for Bapp=2.5 and 3.0 T at TS=5, respectively.
However, the magnetic ﬁeld concentration ratio, Bc/Bapp,
gradually decreased due to increased magnetic ﬂux penetration into the bulk lens. For the ﬁnal stage (TS=10), at which
the external ﬁeld was zero, the Bc value increased negatively
with increasing Bapp for the same reason. For all the cases, theminimum temperature of the GdBaCuO bulk lens encapsulated by the SS holder was only 26.5 K. To improve theperformance of the magnetic lens, lowering its temperature isnecessary.
3.3. Realization of the HTFML

Finally, we present the experimental realization of the
HTFML using GdBaCuO magnetic lens, combined with the
MgB2 bulk cylinder. Figure 7(a) shows the time evolution of
the magnetic ﬁeld, Bc, at the center of the HTFML during themagnetizing process shown in ﬁgure 2 under an external
magnetic ﬁeld of Bapp=2.0 T. Figure 7(b) shows the time
evolution of the temperatures measured at each position. In
the ascending stage, the Bc value reached 3.65 T and thenslightly decreased to 3.55 T at the end of the descending stage
due to ﬂux ﬂow. The magnetic ﬁeld concentration ratio,
Bc/Bapp, was 1.76 at the end of the ramp. The temperatures ofthe MgB2 cylinder and the GdBaCuO bulk lens on the SS
holder were 20.0 and 26.5 K, respectively. These results
demonstrate the HTFML effect experimentally for theﬁrst time.
Figure 8 shows the TS dependence of the magnetic ﬁeld,
Bc, at the center of the HTFML during the magnetizing process under applied ﬁelds of Bapp=1.0–3.0 T. At the end of
the ascending stage (TS=5), the Bc value for each Bapp wasnearly the same as that for the single GdBaCuO magnetic lenscase, as shown in ﬁgure 6. In the descending stage, for
Bapp=1.0 and 2.0 T, the Bc value was nearly the same as thatat TS=5. On the other hand, for Bapp=2.5 and 3.0 T, the Bc
value gradually decreases with increasing TS. As a result, theﬁnal Bc value for Bapp=2.5 and 3.0 T was smaller than thatfor Bapp=2.0 T. The concentrated magnetic ﬁeld, Bc, at
5－ 123 －

Supercond. Sci. Technol. 32 (2019) 12LT03

bore (e.g. 100 mm in ID) has become more readily available
in the science and engineering research communities outsideof the ﬁeld of superconductivity. Thus, building on theseﬁndings, we aim to provide easily a concentrated magnetic
ﬁeld higher than 10 T in an open space using this HTFML
system.

4. Conclusion
We have presented, for the ﬁrst time, the experimental realization of a HTFML, based on the device design and magnetizing procedure recently proposed in [19, 20]. The
important results and conclusions in this study are summarized as follows.
Figure 8. TS dependence of the measured magnetic ﬁeld, Bc, at thecenter of the HTFML device during the magnetization process undervarious applied ﬁelds, Bapp=1.0–3.0 T.

(1) The HTFML effect was demonstrated experimentallyusing GdBaCuO magnetic lens and MgB2 TFM
cylinder for the ﬁrst time, such that a magnetic ﬁeld
can be generated in the central bore of the magnetic lensthat is higher than both the trapped ﬁeld in the single
cylindrical bulk TFM and the external magnetizing
ﬁeld, even after the externally applied ﬁeld decreases
to zero.
(2) A maximum concentrated magnetic ﬁeld of
Bc=3.55 T was achieved in the central bore of the
HTFML device after removing an applied ﬁeld of
Bapp=2.0 T at T=20 K. The maximum Bc value wassmaller than the one estimated by numerical simulations, which results from the lower Jc (B, T) and higher
operating temperature, compared with those of thenumerical predictions.
(3) For higher Bapp, the Bc value was not enhanced becauseof a weakened lens effect due to magnetic ﬂux
penetration into the bulk GdBaCuO material comprising the lens. To enhance the HTFML effect, improving
the thermal contact between the HTFML and the cold
stage and lowering temperature of the GdBaCuO lensand MgB2 TFM cylinder is necessary for the present
setup.

Table 1. Concentrated magnetic ﬁeld, Bc, at TS=5 and 10 at thecenter of the HTFML, and calculated magnetic ﬁeld concentration
ratio, Bc/Bapp for various applied magnetic ﬁelds, Bapp.

Bapp (T)
1.0
2.0
2.5
3.0

Bc (T)
at TS=5

Bc (T)
at TS=10

Bc/Bapp
at TS=10

2.00
3.65
4.45
5.19

1.99
3.55
3.46
3.22

1.99
1.76
1.38
1.07

TS=5 and 10 at the center of the HTFML, and calculated
magnetic ﬁeld concentration ratio, Bc/Bapp, for the various
applied magnetic ﬁelds, Bapp, are summarized in table 1. A
maximum Bc value of 3.55 T was achieved for Bapp=2.0 T.
In the concept paper, in which the HTFML was proposed
to be constructed using a REBaCuO magnetic lens and MgB2
TFM cylinder, a concentrated magnetic ﬁeld Bc=4.73 T was
predicted for an external magnetizing ﬁeld Bapp=3 T using
numerical simulations [19]. However, the maximum Bc value
was as low as 3.55 T experimentally under the same magnetizing process for Bapp=2.0 T. This difference occurs forthe following reasons. Firstly, the assumed Jc (B, T) characteristics of the MgB2 and GdBaCuO bulks used in thesimulations were higher than those of the actual bulks used in
the experiments. Secondly, the minimum temperature of the
GdBaCuO bulk lens was only 26.5 K, when the temperatureof the cold stage was set to 20.0 K. To enhance the HTFML
effect for the present MgB2 cylinder and GdBaCuO bulk lens,
the thermal contact between the GdBaCuO bulk lens and the
SS holder must be improved. Nevertheless, we have realized
the HTFML effect experimentally for the ﬁrst time. Our ﬁnal
goal is to build and test an HTFML using a GdBaCuO
cylinder and GdBaCuO lens, for which a Bc value in excess of
10 T (e.g. Bc=13.5 T [19]) is predicted for a magnetizing
process with Bapp=10 T. A cryocooled 10 T superconducting solenoid magnet with a large room temperature

Acknowledgments
The authors thank Mr Y Yanagi of IMRA Material R&D Co.,
Ltd, Japan, and Dr G Giunchi of Materials Science Consultant, Italy, for their valuable experimental supports. This
research is supported by Adaptable and Seamless Technology
transfer Program through Target-driven R&D (A-STEP) fromJapan Science and Technology Agency (JST), Grant No.
VP30218088419 and by JSPS KAKENHI Grant No.
19K05240. M D Ainslie would like to acknowledge ﬁnancial
support from an Engineering and Physical Sciences ResearchCouncil (EPSRC) Early Career Fellowship, EP/P020313/1.
All data are provided in full in the results section of thispaper.
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Supercond. Sci. Technol. 32 (2019) 12LT03

ORCID iDs

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Supercond. Sci. Technol. 32 065001

Sora Namba https://orcid.org/0000-0001-7268-5326
Hiroyuki Fujishiro https://orcid.org/0000-00031483-835X
Tomoyuki Naito https://orcid.org/0000-0001-7594-3466
Mark D Ainslie https://orcid.org/0000-0003-0466-3680
Keita Takahashi https://orcid.org/0000-0002-8278-2688
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8. (I-25) Tatsuya Hirano, Yuhei Takahashi, Sora Namba, Tomoyuki Naito and
Hiroyuki Fujishiro,“A record-high trapped field of 1.61 T in MgB2 bulk comprised of copper plates
and soft iron yoke cylinder using pulsed-field magnetization”,
Supercond. Sci. Technol. 33 (2020) 085002 (10 pages) (No. 276 paper)78－ 126 －

Superconductor Science and Technology
Supercond. Sci. Technol. 33 (2020) 085002 (10pp)

https://doi.org/10.1088/1361-6668/ab9542

A record-high trapped field of 1.61 T in
MgB2 bulk comprised of copper plates
and soft iron yoke cylinder using
pulsed-field magnetization
Tatsuya Hirano, Yuhei Takahashi, Sora Namba, Tomoyuki Naito andHiroyuki Fujishiro
Department of Physical Science and Materials Engineering, Faculty of Science and Engineering, Iwate
University, Morioka 020-8551, Japan
E-mail: fujishiro@iwate-u.ac.jp and thirano1995@gmail.com
Received 10 March 2020, revised 3 May 2020
Accepted for publication 21 May 2020
Published 18 June 2020
Abstract

A trapped field of BT = 1.61 T was experimentally achieved at the central surface of an MgB2
bulk composite (60 mm in diameter and 20 mm in height) at 20 K by double pulsed-fieldmagnetization (PFM) using a split-type coil. The composite bulks consisted of two MgB2 ringbulks sandwiched by thin copper ring plates, which were then stacked, and a soft iron yoke
cylinder was inserted in the central bore of the rings. The copper ring plates delayed the rise timeand duration of the magnetic pulse due to eddy currents. The inserted soft iron yoke attracted themagnetic flux and enhanced the trapped field strength mainly due to its large permeability. As aresult, the trapped field was enhanced from BT = 0.34 T for the single MgB2 ring bulk without
the copper plates and soft iron yoke to BT = 1.00 T for the composite with both copper plates
and the soft iron yoke. The inserted soft iron yoke can be exploited to enhance the trapped field
because the intrinsic BT of the single MgB2 ring bulk was smaller than the saturation field of theyoke (∼2 T). Using an optimized second pulse application after suitable flux trapping from thefirst pulse application, the trapped field was enhanced considerably to BT (2nd) = 1.61 T, which
is a record-high trapped field for an MgB2 bulk by PFM to date. The combination of the longer
magnetic pulse application by the copper plates, the enhancement of the effective applied fieldby the inserted soft iron yoke, and the double pulse application using split-type coil is aneffective technique to enhance the trapped field in the MgB2 bulk using PFM.
Keywords: MgB2 , pulsed field magnetization, trapped field, soft iron yoke cylinder, double pulse
application, copper plate stack, rise time elongation(Some figures may appear in colour only in the online journal)
1. Introduction

systems and compact cryogen-free nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems[2–6]. A record high trapped field of BT (FCM) = 17.6 T at
26 K has been achieved in the GdBaCuO disk bulk pair activated by field-cooled magnetization (FCM) [7, 8]. During FCM,
the bulk is cooled below the transition temperature, T c = 92 K,
under the applied field, Bex , using superconducting magnet(SM) and then the magnetic field decreases to zero.

Large, single-grain RE-Ba-Cu-O (REBaCuO, RE: a rare earth
element or Y) bulk superconductors can trap higher magnetic
field by strong vortex pinning effect and are a promising material for use as a compact, high-strength trapped field magnet(TFM) [1] for various practical applications, such as rotating machines, magnetic separation, flywheel energy storage1361-6668/20/085002+10$33.00

1－ 127 －© 2020 IOP Publishing Ltd

Printed in the UK

Supercond. Sci. Technol. 33 (2020) 085002

T Hirano et al

the REBaCuO bulk [17, 23, 24], the use of soft iron yoke inthe pulse coil [19] and the long pulse application [37].
In this study, we have investigated the trapped field properties of MgB2 ring bulk composites inserted by soft iron yokeat 20 K by single and double pulsed field applications using
a split-type coil. Furthermore, the effect of thin copper plates,
which sandwiched the MgB2 ring bulks, was investigated to
expect the longer magnetic pulse application. As a result, a
new record-high trapped field of BT = 1.61 T was experimentally achieved at 20 K for an MgB2 ring bulk comprised of bothcopper plates and a soft iron yoke using double pulsed-field
application by split-type coil.

On the other hand, MgB2 bulk superconductors have also
promising potential as TFMs, such as being rare-earth-free,lightweight and presenting a homogeneous trapped field distribution [9], which are in clear contrast with REBaCuO bulks.
The better and larger MgB2 polycrystalline TFMs can berealized because of their long coherence length, ξ, below
T c = 39 K [10]. MgB2 bulks with high critical current density, J c , have been fabricated by various methods and usuallyactivated by FCM [11–15]. A record-high trapped field of
BT (FCM) = 5.4 T has been achieved at 12 K on a surface of a
MgB2 disk bulk 20 mm in diameter [16]. In this way, FCM canachieve the maximum trapped field of the bulk. However, since
the SM is expensive and heavy, FCM is generally ill-suited forwide practical applications.
Pulsed-field magnetization (PFM) is another magnetizing
method to magnetize bulk superconductors [17–21], which ismobile, inexpensive experimental setup with no use of SM.
During PFM, the bulk is cooled below T c , and the magnetic
pulsed field with the rise time of milliseconds is applied using acopper coil and condenser bank. However, the trapped field byPFM, BT (PFM), is generally lower than that by FCM becauseof a large temperature rise caused by the dynamics of the magnetic flux during the magnetic pulse application [22].
Multi-pulse techniques are effective to enhance the BT
value for REBaCuO bulks due to the reduction of the temperature rise [23–26]. We have achieved the trapped field of
BT (PFM) = 5.20 T on a GdBaCuO bulk 45 mm in diameterat 29 K using a modified multi-pulse technique with stepwise
cooling (MMPSC) [17], which is a record-high BT (PFM) for
REBaCuO bulk by PFM to date. The PFM technique has also
been applied to MgB2 bulks [27–32]. BT (PFM) = 0.81 T wasachieved at 14 K for a high-J c MgB2 bulk fabricated by the
hot isostatic pressing (HIP) method magnetized using a copper solenoid coil, in which BT (FCM) = 2.23 T was trapped at
16 K by FCM [29]. However, flux jumps took place frequently
during PFM in the high-J c MgB2 bulks and consequently the
final BT (PFM) value decreased for larger pulsed fields. The
multi-pulse application would be to enhance the trapped field
for the MgB2 bulk.
The effectiveness of the split-type coil (or vortex-type coil)during PFM has been clarified for REBaCuO bulks experimentally [33, 34] and numerically [19, 35]. The magnetic flux
starts to intrude not from the periphery, but mainly from theboth surfaces of the disk bulk, and is trapped in the centerof the bulk, even for lower pulsed fields. It was shown thatthe maximum BT could be enhanced in comparison to thatobtained using the solenoid-type coil. In this case, the temperature rise during PFM for the split-type coil was smaller thanthat for the solenoid-type coil. We have achieved a trappedfield of BT (PFM) = 1.1 T on a high-J c MgB2 bulk at 13 K
without flux jumps by PFM using a split-type coil, in which apair of soft iron yokes were inserted in the bore of the splittype coil. BT (PFM) = 1.1 T has been the record high trappedfield by PFM for MgB2 bulk since 2016 [36]. We have performed many PFM experiments and numerical simulations for
REBaCuO and MgB2 bulks, in which the following effectiveness has been suggested to enhance the trapped field; the useof split-type coil [19, 33–35], the multi-pulse application for

2. Experimental details
We performed the PFM experiments using three types of bulk
modules. An MgB2 ring bulk (20 mm in inner diameter (I.D.),
60 mm in outer diameter (O.D.) and 19 mm in height (H))
was fabricated by an in-situ infiltration method [38], in which
BT (FCM) = 1.57 T was trapped by FCM at 20 K. We abbreviate this as ‘single bulk’, as shown in figure 1(a). The single
bulk was sliced in half (H = 9 mm), and each ring bulk was
sandwiched by oxygen-free copper plates 0.5 mm in thickness using Apiezon-NTM grease, and then stacked, as shownin figure 1(b). We abbreviate this as ‘composite (w/o yoke)’.
A soft iron yoke cylinder (20 mm in diameter and 20 mm in H)
was inserted in the composite (w/o yoke), as shown in figure1(c). We abbreviate this as ‘composite (w/yoke)’.
Figure 2 shows the experimental setup for PFM using the
split-type coil. Each MgB2 bulk module was fastened in a brassholder using a stainless steel (SS) bolt and nut with thin indium
foil and connected to the cold stage of a Gifford–McMahon(GM) cycle helium refrigerator in a vacuum chamber. In theprevious study, a copper holder was used to fasten the disk
bulk for the split-type coil [19], in which non-negligible temperature rise was observed due to the eddy current flowing in
the holder during PFM. To eliminate the temperature rise in theholder, a brass holder was used in this study, which has lower
electrical conductivity. A Hall sensor (HG-106 C; ASAHIKASEI) was placed to the center of the bulk surface, and athermometer (CernoxTM ) was connected to the brass holder.
The split-type coil (72 mm in I.D., 124 mm in O.D., 35 mm inH), which was submerged in liquid nitrogen, was placed outside the vacuum chamber, in which a pair of Ni-plated soft ironyokes (60 mm in diameter and 65 mm in height) was inserted
in the central bores of the coil.
The strength of the magnetic pulse was estimated using thefollowing methods. Figure 3 shows the experimental method
to estimate the magnitude of pulsed field, Bex (shunt) andBex (Hall). The time evolution of magnetic field, Bex (shunt)(t),was estimated by observing the current, I(t), flowing throughthe shunt resistor from the pulse current source (condenserbank) using a digital oscilloscope (YOKOGAWA Electric,
DL1640). For example, to achieve Bex (shunt)max = 1.5 T at
the center of the split coil at T s = 40 K (>T c of the MgB2bulk), I peak = 440 A. The time evolution of the magnetic field,
Bex (Hall)(t), was also simultaneously monitored at the central
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Figure 1. Three types of MgB2 bulk modules used for the PFM experiments: (a) ‘single bulk’, (b) ‘composite (w/o yoke)’, where two sliced

ring bulks were sandwiched by oxygen-free copper plates and are stacked, and (c) ‘composite (w/yoke)’, where a soft iron yoke cylinder isinserted in (b).

Figure 2. Experimental setup of the PFM for the three types of bulk modules using split-type coil with soft iron yoke.

surface of the single MgB2 ring bulk and the composite (w/oyoke) by measuring the Hall voltage of the Hall sensor using
the digital oscilloscope. For the composite (w/yoke), the time
evolution of magnetic field, Bex (Hall)(t), which is defined as
Bex (yoke)(t) hereafter, was monitored by measuring the Hall
voltage at the central surface of the soft iron yoke.
The initial temperature, T s , of the bulk was set to 20 K, anda single magnetic pulse, Bex (Hall)(t), with a peak up to 2.0 T
was applied via a pulsed current flowing in the coil, as shown infigure 4(a). The PFM experiments were also performed using
double pulse application, as shown in figure 4(b). The first
pulse of Bex1 (Hall)max = 1.20 or 1.32 T was applied at 20 K.
Next, once the temperature of the bulk returned to 20 K, thesecond pulse, Bex2 (Hall)max , ranging from 1.1 to 1.6 T, wasapplied to the bulk.
During PFM, the time evolution of the temperature, T(t),and the trapped field, BT , which was defined as the final valueof BT (t) at 500 ms, were measured. After the removal of the3－ 129 －

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Figure 3. The experimental method to estimate the magnitude of pulsed field, Bex (shunt) and Bex (Hall).

Figure 4. Schematic illustration of (a) single-pulse and (b) double-pulse application during PFM at T s = 20 K.

split-type coil (15 min after the each pulse application), twodimensional trapped field profiles were mapped at 5 mm above
the bulk surface (on the outer surface of the vacuum chamber)by scanning a Hall sensor (BHA 921; F W Bell) using an x–ystage controller.

(w/yoke) cases are quite different with those for the single
bulk case.
Figure 5(b) shows the relationship between the maximum values (Bex (Hall)max and Bex (shunt)max ) of the curves
Bex (Hall)(t) and Bex (shunt)(t) for each case at T s = 40 K.
The maximum value of the Bex (Hall)(t) curve, named as
Bex (Hall)max for the composite (w/o yoke) was about 20%
smaller than that of the Bex (shunt)(t), named as Bex (shunt)max ,because of eddy currents flowing in the high-conductive copper plates along the direction to avoid the magnetic flux
intrusion. On the other hand, the Bex (Hall)max value for thecomposite (w/yoke) was much larger than Bex (shunt)max ,and its rate increases with increasing Bex (shunt)max . The
Bex (Hall)max enhancement for the composite (w/yoke) mainly
results from flux concentration in the ferromagnetic yoke cylinder, although the induced current flowing in the yoke acts to
reduce the flux intrusion.
Figure 5(c) shows the rise time, trise (Hall), measured by
the Hall sensor and trise (shunt), as a function of Bex (shunt)max
at T s = 40 K. The magnitude of trise (Hall) for the composite (w/o yoke) increased due to the copper plates, and that forthe composite (w/yoke) increased more due to the existence ofthe yoke, compared with that for the single bulk. The detailed
study using the copper plates is planned in the next paper.

3. Results and discussion
3.1. Effect of the copper plates and soft iron yokeFirst, we clarify the effects of the copper plate stack and softiron yoke insertion on the magnetic pulse, Bex (t). Figure 5(a)shows the time dependence of Bex (shunt)(t) for an appliedmagnetic field of 1.03 T, which was measured for the ‘single
bulk’ case at T s = 40 K. The rise time, trise , was about 20 ms,
and the pulse duration was about 400 ms, which were determined by the coil inductance and the existence of the ferromagnetic soft iron yoke inserted in the bore of the split-type
coil. In the figure, the Bex (Hall)(t) profiles for the single bulk,
composite (w/o yoke) and composite (w/yoke) cases are also
shown, which were measured by the adhered Hall sensors.
Bex (Hall)(t) for the single bulk was slightly delayed, compared with Bex (shunt)(t). However, the magnitude, rise timeand duration of Bex (Hall)(t) for the composites (w/o yoke) and4－ 130 －

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Figure 5. (a) The time dependence of Bex (shunt)(t) for an applied magnetic field of 1.03 T, measured for the single MgB2 bulk case, andBex (Hall)(t) for the single bulk, composite (w/o yoke) and composite (w/yoke) cases at T s = 40 K. (b) The relationship between the
maximum values (Bex (Hall)max and Bex (shunt)max ) of the curves Bex (shunt)(t) and Bex (Hall)(t) for each case at T s = 40 K. (c) The rise time,trise (Hall) and trise (shunt), as a function of Bex (shunt)max at T s = 40 K.

yoke) was slightly larger than that for the single bulk case.
For the composite (w/yoke), the magnetic flux started to penetrate into the center around Bex (Hall)max = 1.03 T, took amaximum of BT = 1.00 T at Bex (Hall)max = 1.20 T, and thendecreased with increasing Bex (Hall)max . It should be noted thatfor the composite (w/yoke), the BT value was enhanced, but theBex (Hall)max value at which BT value took a maximum wasnearly the same as that for the composite (w/o yoke). These
results suggest that the enhancement of the BT value resulted
mainly from the yoke cylinder and that the Bex (Hall)max value
at which BT value takes a maximum was mainly determined by
the copper plates, although we did not perform PFM experiments for the MgB2 bulk with only the yoke without the copper
plates.
Figure 7(a) shows the maximum temperature rise, T max ,during PFM for each composite, as a function of Bex (Hall)max
at 20 K. For the single bulk, T max abruptly increases at
Bex (Hall)max = 0.85 T due to the pinning loss of the flux trap[39], at which the magnetic flux reached the center of the bulk,
and BT = 0.34 T was trapped. T max increased with increasing Bex (Hall)max due to the viscous loss of the flux movement[39]. For the composites (w/yoke) and (w/o yoke) cases, T max
linearly increased with increasing Bex (Hall)max , even though
the magnetic flux was not trapped the center of the bulk for3.2. Results for single pulse application

The PFM experiments were performed for the three types of
MgB2 modules at T s = 20 K (<T c of the MgB2 bulk). Figure 6
shows the trapped field, BT , which is defined as the steadyvalue of the curves BT (t) at t = 500 ms, at the central surfaceof each MgB2 module, as a function of Bex (Hall)max at 20 K.
The trapped field profiles for each case, when the maximum
BT value was achieved, are also shown. For the single MgB2
bulk case, the magnetic flux started to penetrate into the center at Bex (Hall)max = 0.85 T, and a maximum of BT = 0.34 T
was trapped at the central surface. For larger Bex (Hall)max ,the BT value decreased due to a larger temperature rise. The
trapped field profile is shown, for which a trapezoidal profile was measured 5 mm above the bulk surface. For the composite (w/o yoke), the magnetic flux started to penetrate into
the center at Bex (Hall)max = 1.23 T, and then decreased withincreasing Bex (Hall)max . A maximum BT = 0.44 T was trappedat the central surface. The Bex (Hall)max value for the composite (w/o yoke), at which the BT value took a maximum,
was larger than that for the single MgB2 bulk. Here, a larger
magnetic pulse is necessary to trap the magnetic flux at thecenter due to the existence of the copper plates, as shown infigure 5(b). The maximum BT value for the composite (w/o5

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Figure 6. The trapped field, BT , at the central surface of each module, as a function of Bex (Hall)max at 20 K. The trapped field profiles foreach case, when the maximum BT value was achieved, are also shown.

Bex (Hall)max < 1.2 T. These results indicate that the heat generation took place mainly in the copper plates due to the eddy
currents in addition to the heat generation due to the flux trap.
For Bex (Hall)max > 1.2 T, for which the magnetic flux wastrapped, the temperature rise due to the flux trap was superimposed and T max was larger than that of the single bulk. Becauseof the additional heat generation from the eddy current in theinserted yoke, the temperature rise of the composite (w/yoke)
was larger than that of the composite (w/o yoke) for higher
Bex (Hall)max .
Figure 7(b) shows an example of the time dependenceof the temperature, T(t), in the composite (w/o yoke) forBex (Hall)max = 0.91, 1.23 and 1.29 T, which was measured
on the surface of the brass holder. T(t) took a maximum
at t = 2 ∼ 3 s and then linearly decreased with increasing time. The maximum temperature increased with increasing Bex (Hall)max . Similar trends were also observed for othercases. The results in figure 7 reflect indirectly the trapped field
properties during PFM, even though the thermometer was notadhered directly on the bulk surface.
Figure 8 shows the time dependence of the applied field,
Bex (t), and the trapped field, BT (t), for each case and foreach single pulse application of Bex (Hall)max . Figures 8(a) to(c) show the results for the single MgB2 ring bulk, where
Bex (shunt)(t) and Bex (Hall)(t) are also shown. The magnetic
flux cannot penetrate well to the center of the bulk due to its
magnetic shielding for Bex (Hall)max = 0.83 T (figure 8(a)).
With increasing Bex (Hall)max , the magnetic flux was able topenetrate into the center, and the BT (t = 500 ms) value
took a maximum at Bex (Hall)max = 0.85 T (figure 8(b)). For
Bex (Hall)max = 0.88 T, the BT (t = 500 ms) value decreased
due to a large flux flow out of the bulk (figure 8(c)). Figures
8(d) to (f) show the results for the composite (w/o yoke). Here,similar trends to the single bulk were observed. The BT value
took a maximum of BT = 0.42 T at Bex (Hall)max = 1.23 T(figure 8(e)), and then decreased at Bex (Hall)max = 1.30 T. For

higher Bex (Hall)max , as shown in figure 8(f), a long gradualdecay in BT (t) can be seen at 100 ms < t < 250 ms. This isa characteristic decay in MgB2 bulk during PFM [30], which
was also reported by other researcher [32], but has not beenclarified the reason. Figures 8(g) to (i) show the results forthe composite (w/yoke), where Bex (yoke)(t) is also shown, in
addition to Bex (shunt)(t) and Bex (Hall)(t). The BT value took amaximum of 1.00 T at Bex (Hall)max = 1.21 T (figure 8(h)) andthen decreased at Bex (Hall)max = 1.32 T. The trapped field of
the composite (w/yoke) was higher than that of the composite (w/o yoke), because the iron yoke has a large permeability.
The period of the characteristic BT (t) decay for the composite(w/yoke) becomes longer at 150 ms < t < 400 ms. These results
indicate that the composite bulk is considered to be pseudolong pulsed field magnetization technique.

3.3. Results for double pulse application

In the previous subsection, the effects of the copper plates
on the MgB2 bulk surface and the insertion of soft ironyoke cylinder on the trapped field enhancement were clearly
confirmed for the single pulse application. In this subsection, the effect of the double pulse application is presented.
Figure 9(a) shows the trapped field, BT (2nd), on the central
surface of the composite (w/yoke) at T s = 20 K, as a function of the second applied pulsed field, Bex2 (Hall)max , after
the first pulsed field, Bex1 (Hall)max , of 1.20 T or 1.32 T wasapplied and the magnetic flux was already trapped. Afterthe application of Bex1 (Hall)max = 1.32 T, the final BT (2nd)value was 0.65 T, as shown in figure 8(i). For the second
pulse application, BT (2nd) sharply increased, took a maximum of 1.61 T at Bex2 (Hall)max = 1.26 T, and then decreased
with increasing Bex2 (Hall)max . The BT (2nd) = 1.61 T is arecord high BT value for an MgB2 bulk by PFM to date. The
trapped field profile 5 mm above the bulk surface was fairly
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Figure 7. The maximum temperature rise, T max , during PFM for each composite, as a function of Bex (Hall)max at 20 K. (b) An example ofthe time dependence of the temperature, T(t), for the composite (w/o yoke) for Bex (Hall)max = 0.91, 1.23 and 1.29 T at 20 K.

Figure 8. The time dependence of the applied fields, Bex (t), and the trapped field, BT (t), for single pulse application of Bex (Hall)max for(a)–(c) the single bulk, (d)–(f) the composite (w/o yoke), and (g)–(i) the composite (w/yoke).

cone shaped. The highest BT value comes from the reduction of temperature rise due to the already trapped magnetic
flux during the 1st magnetic pulse [17, 40]. For the case of
Bex1 (Hall)max = 1.20 T, similar BT (2nd) vs Bex2 (Hall)max behavior can be observed. However, the maximum BT (2nd) value
was smaller than that for Bex1 (Hall)max = 1.32 T. These results suggest that an optimum trapped field and BT (1st) profile

exists to maximize the BT (2nd) value. Figure 9(b) shows the
maximum temperature rise, T max , of the composite (w/yoke)
at T s = 20 K, as a function of second applied pulsed field,
Bex2 (Hall)max . T max for the single pulse application of the composite (w/yoke) at T s = 20 K is also shown, which was presented in figure 7(a). It should be noted that T max after the second
pulse application is about 2 K smaller than that for the single
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Figure 9. (a) The trapped field, BT (2nd), on the central surface of the composite (w/yoke) at T s = 20 K, as a function of the second
applied pulsed field, Bex2 (Hall), after the first pulsed fields, Bex1 (Hall)max , of 1.20 T and 1.32 T were applied. The trapped field profiles of
the composite (w/yoke) measured 5 mm above the bulk surface at 20 K, for which the maximum BT (2nd) was achieved for
Bex1 (Hall)max = 1.20 T and 1.32 T. (b) The maximum temperature rise, T max , of the composite (w/yoke) at T s = 20 K, as a function of
Bex2 (Hall)max . T max for the single pulse application for the composite (w/yoke) at T s = 20 K is also shown.

Figure 10. The time dependence of the applied fields, Bex2 (t), and the trapped field, BT (2nd)(t) for the second pulse application,
Bex2 (Hall)max , after the first pulse application of (a)–(c) Bex1 (Hall)max = 1.32 T and (d)–(f) Bex1 (Hall)max = 1.21 T at T s = 20 K.

at T s = 20 K for Bex2 (Hall)max = 1.17, 1.26 and 1.50 T, after
the first pulse of Bex1 (Hall)max = 1.32 T was applied. The
time dependence of BT (1st)(t) for Bex1 (Hall)max = 1.32 T wasshown in figure 8(i), in which BT (1st) = 0.65 T was trapped.
For Bex2 (Hall)max = 1.26 T, the maximum BT (2nd) of 1.61 T

pulse application. The reduction of temperature rise results inthe enhancement of BT after the second pulse.
Figures 10(a)–(c), respectively, show the time dependenceof the applied fields, Bex2 (shunt)(t), Bex2 (Hall)(t) for w/o yoke
and Bex2 (yoke)(t) for w/yoke, and the trapped field, BT (2nd)(t),8－ 134 －

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was achieved. Figures 10(d)–(f), respectively, show the timedependence of applied fields and the trapped field, BT (2nd)(t),
at T s = 20 K for Bex2 (Hall)max = 1.21, 1.26 and 1.52 T, after
the first pulse of Bex1 (Hall)max = 1.20 T was applied. The
time dependence of BT (1st)(t) for Bex1 (Hall)max = 1.21 T wasshown in figure 8(h), in which BT (1st) = 1.00 T was trapped.
As shown in figure 9(a), a similar trend can be seen after
the Bex1 (Hall)max application of 1.32 and 1.20 T, althougha slight difference in the maximum value of BT (2nd) exists.
However, the BT (t) behavior was different after the identical
Bex2 (Hall)max = 1.26 T application, as shown in figures 10(b)and (e). In the case of Bex1 (Hall)max = 1.32 T, which was
higher than the optimum Bex1 (Hall)max shown in figure 6,
BT (1st) was as low as 0.65 T. For the 2nd pulse applicationof Bex2 (Hall)max = 1.26 T, a clear BT (2nd)(t) enhancement up
to 1.61 T can be observed. On the other hand, in the case of
Bex1 (Hall)max = 1.20 T, which was the optimum Bex1 (Hall)max
shown in figure 6, BT (1st) was 1.00 T. For the 2nd pulse application of Bex2 (Hall)max = 1.26 T, the BT (2nd)(t) enhancement
was relatively small. These results suggest that the enhancement of BT (2nd) is sensitive to the trapped field profile inthe bulk after the 1st pulse application. A similar trend in theenhancement of BT (2nd) was observed in the results from the
MMPSC method for the GdBaCuO bulk in [17].

(4) The combination of the longer magnetic pulse by the copper plates, the enhancement of the effective applied fieldby the inserted soft iron yoke and the double pulse application using the split-type coil is an effective technique toenhance the trapped field in the MgB2 bulk using PFM.
This composite structure with copper plates and an ironyoke may also be applicable to REBaCuO bulk trappedfield magnets magnetized by PFM.
Acknowledgments
The authors thank Dr Mark D Ainslie of University of Cambridge for his valuable discussions and suggestions. This
research is supported by Adaptable and Seamless Technology transfer Program through Target-driven R&D (A-STEP)
from Japan Science and Technology Agency (JST), Grant
No. VP30218088419 and by JSPS KAKENHI Grant No.
19K05240.
ORCID iDs
Tatsuya Hirano  https://orcid.org/0000-0003-1658-914X
Sora Namba  https://orcid.org/0000-0001-7268-5326
Tomoyuki Naito  https://orcid.org/0000-0001-7594-3466
Hiroyuki Fujishiro  https://orcid.org/0000-0003-1483835X

4. Conclusion
We have investigated the pulsed field magnetization (PFM) of
three types of MgB2 bulk modules (single ring bulk, composite (w/o yoke) and composite (w/yoke)) using a split-type coil(also inserting a soft iron yoke) at T s = 20 K. The composite(w/o yoke) consisted of two MgB2 ring bulks sandwiched bythin oxygen-free copper ring plates, which were then stacked.
The composite (w/yoke) module included a soft iron yoke cylinder that was inserted in the composite (w/o yoke). We alsostudied the effect of the copper plates and soft iron yoke toenhance the trapped field, BT . The important results and conclusions are summarized as follows.

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9. (H-8) K. Takahashi, H. Fujishiro and M. D. Ainslie,“A conceptual study of a high gradient trapped field magnet (HG-TFM) providing
toward a quasi-zero gravity space on Earth”,
Supercond. Sci. Technol. 34 (2021) 035001 (13 pages) (No. 283 paper)79－ 137 －

Superconductor Science and Technology
Supercond. Sci. Technol. 34 (2021) 035001 (13pp)

https://doi.org/10.1088/1361-6668/abd386

A conceptual study of a high gradient
trapped field magnet (HG-TFM) toward
providing a quasi-zero gravity space on
Earth
Keita Takahashi1, Hiroyuki Fujishiro1 and Mark D Ainslie2
1

Department of Physical Science and Materials Engineering, Faculty of Science and Engineering,
Iwate University, Morioka 020-8551, Japan2
Bulk Superconductivity Group, Department of Engineering, University of Cambridge, Cambridge CB2
1PZ, United Kingdom
E-mail: s3119004@iwate-u.ac.jp and fujishiro@iwate-u.ac.jp
Received 23 September 2020, revised 18 November 2020
Accepted for publication 14 December 2020
Published 25 January 2021
Abstract

In this work, we propose a new concept of a high gradient trapped field magnet (HG-TFM). The
HG-TFM is made from (RE)BaCuO bulk superconductors, in which slit ring bulks (slit-TFMs)
are tightly stacked with TFM cylinders (full-TFMs), and state-of-the-art numerical simulations
were used to investigate the magnetic and mechanical properties in detail during and aftermagnetization. A maximum value of the magnetic field gradient product ofBz · dBz /dz = 6040 T2 m−1 was obtained after conventional field cooled magnetization (FCM)with an applied field, Bapp , of 10 T of the HG-TFM with 60 mm in outer diameter and 10 mm in
inner diameter. This value may be the highest value ever reported compared to any othermagnetic sources. The Bz · dBz /dz value increased with decreasing inner diameter of the
HG-TFM and with increasing Bapp during FCM. The electromagnetic stress in the HG-TFM
during the FCM process mainly results from the hoop stress along the circumferential direction.
The simulations suggested that there is no fracture risk of the bulk components during FCM
from 10 T in a proposed realistic configuration of the HG-TFM where both TFM parts aremounted in Al-alloy rings and the whole HG-TFM is encapsulated in a steel capsule. A
quasi-zero gravity space can be realized in the HG-TFM with a high Bz · dBz /dz value in an open
space outside the vacuum chamber. The HG-TFM device can act as a compact and cryogen-freedesktop-type magnetic source to provide a large magnetic force and could be useful in a numberof life/medical science applications, such as protein crystallization and cell culture.
Keywords: bulk superconductors, trapped field magnets, high gradient magnets, finite element
method, magnetic levitation, quasi-zero gravity(Some figures may appear in colour only in the online journal)

Original content from this work may be used under the termsof the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and thetitle of the work, journal citation and DOI.
1361-6668/21/035001+13$33.00

1－ 138 －© 2021 The Author(s). Published by IOP Publishing Ltd

Printed in the UK

Supercond. Sci. Technol. 34 (2021) 035001

K Takahashi et al

1. Introduction

zero-resistivity due to electromagnetic induction after applying and removing a large magnetizing field. Such (RE)BaCuO
bulks with a critical temperature, T c , over 90 K are the mostpromising materials to be utilized as a trapped field magnet(TFM) in a compact and desktop-type magnetic source. The
record-high trapped field, 17.6 T, was achieved at the centerof a two-stack GdBaCuO bulk pair magnetized by field-cooledmagnetization (FCM) at 26 K using outer shrink-fit stainlesssteel (SS) rings [7] as well as at 23 K using SS laminations[8]. Regarding the validity of bulk TFMs magnetized by FCM,
Vakaliuk et al indicated that the reproducibility of the trappedfield can be verified experimentally under the applied field of
10 T at 50 K, but might not be proved for higher fields over
Bapp = 14 T [9]. The exploration of practical use of such strong
TFMs can be classified into three phases: fabrication, magnetization, and applications [6, 10]. Such experimental work
has showed the significant potential of such TFMs as a powerful magnetic source. However, its configuration would not beappropriate for practical use in applications, which sometimes
require the large magnetic field and/or gradient product to beprovided in an open space inside or outside vacuum chamber.
Recently, the authors proposed a new concept of the hybrid
TFM lens (HTFML), consisting of two bulk parts: an innerbulk lens and outer bulk cylinder [11]. The diamagnetic lenseffect of the inner bulk lens can concentrate the trapped field
generated from the outer bulk TFM cylinder after magnetization. It was predicted numerically that an HTFML consistingof a GdBaCuO bulk lens and GdBaCuO TFM cylinder can
generate a concentrated magnetic field of Bc = 11.4 T at 20 K
that is higher than the external magnetic field of Bapp = 10 T,
quasi-permanently without any additional power consumption[12]. Experimental validation has proved the feasibility of the
HTFML, exploiting an inner GdBaCuO bulk lens and outer
MgB2 TFM cylinder, in which Bc = 3.5 T was achieved for
Bapp = 2.0 T at 20 K [13]. This HTFML device suggests
a new pathway to enhance the trapped field from the viewpoint of the magnetizing method in contrast to conventional
approaches that depend on the superconducting properties ofthe bulk itself.
Additionally, in the case of the HTFML using a
GdBaCuO bulk lens and GdBaCuO TFM cylinder, we
showed that a magnetic field gradient product as high as
Bz · dBz /dz = −3000 T2 m−1 could be generated inside thebulk annuli under the concentrated trapped field of Bc = 11.4 T
at 20 K, which allows for a quasi-zero gravity environment ina cost-effective and efficient way [12]. However, the HTFML
device has some challenges in its construction and the magnetizing process. The temperature of the GdBaCuO bulk lensand the GdBaCuO TFM cylinder must be controlled individually during zero field-cooled magnetization (ZFCM) for thelens part and FCM for the TFM part. A special technique isrequired in order to control the temperature separately and themagnetization process can take several hours. Moreover, it isquite difficult to realize a room temperature bore for practicalapplications exploiting the advantages of the HTFML becauseof a narrow bore less than 10 mm in diameter in the GdBaCuO
lens, which is also encapsulated in a SS holder. This does limit
the effective size for practical scientific experiments.

Zero gravity in space is known to be a characteristic condition in scientific research fields. Up to now, some experimental
research has been carried out exploiting quasi-zero gravity
conditions in the International Space Station as an environmental parameter, which focuses positively on applications
related to life/medical sciences, such as protein crystallization [1] and cell culture [2] without natural convection causedby the gravitational force of the Earth. The so-called ‘spacebiology’ resulting from this research is an important developing field that could contribute significantly to the sustainable
development goals.
A large magnetic field in combination with a large field
gradient can provide a repulsive force against gravity on the
Earth and achieve a counter-balance situation for any diamagnetic materials such as water, common metals and even cells of
the human body. In 1990, magnetic levitation of diamagnetic
materials such as water and plastics was first demonstrated by
Beaugnon et al using a hybrid-type superconducting magnet(HM), in which a magnetic field gradient product, Bz · dBz /dz,
as high as −1923 T2 m−1 was applied along the vertical direction against gravity on Earth [3].
Superconducting technologies have satisfied several
demands for high magnetic fields including magnetic levitation. Nikolayev et al summarizes the specification of existing superconducting magnets worldwide, where the highest
Bz · dBz /dz = −3000 T2 m−1 with a record-high magnetic
field of 30 T has been ever achieved in a HM and superconducting coil magnet (SM) [4]. Cryo-cooled superconducting
magnets without liquid helium that can generate Bz · dBz /dz
up to −400 T2 m−1 with magnetic fields up to 10–12 T are
now used practically at the laboratory scale.
The magnetic force, F m , acting on a material increases inproportional to the magnetic field, Bz , and the magnetic field
gradient, dBz /dz, along the z-axis (upper direction) as follows,z
Fm ∝ Bz · dB
dz .

(1)

To enhance F m , there are some trends related to the magnet
design, i.e. the improvement of Bz and/or dBz /dz. One example
is the gradient-type superconducting magnet developed forprotein crystallization, in which an inverse coil made from
Nb3 Sn was placed on the hybrid coil, consisting of an inner
Nb3 Sn coil and outer NbTi coils. As a result, the magnet cangenerate a Bz · dBz /dz as large as −1500 T2 m−1 around theboundary of both coils [5]. The most significant issue is thatsuch a comparatively large Bz · dBz /dz value has been realized
only in a specialized facility [4]. For practical use of a magnetic quasi-zero gravity condition on ground, it is desirable
for the magnetic source to be lightweight, mobile, and costeffective as a desktop-type apparatus, and preferably cryogenfree, i.e. operating without the need for any coolant such as
liquid helium.
Large, single-grain (RE)BaCuO bulk superconductors (RE:rare earth element or Y) can be utilized as a compact andstrong, quasi-permanent magnet [6]. Magnetic flux is trappedin bulk superconductors by a supercurrent flowing with2

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Figure 1. (a) Cross-sectional schematic of the three-dimensional numerical model of the HG-TFM, in which a conventional ring-shaped

TFM cylinder, labelled ‘full-TFM’ (yellow), is sandwiched by two TFM cylinders with slits 10 deg. wide in the diagonal direction, labelled‘slit-TFM’ (orange). The top views of the full-TFM and slit-TFM are also shown in (b) and (c), respectively.

In this study, we propose a new high gradient TFM (hereafter referred to as HG-TFM) to realize a quasi-zero gravity environment, in which slit ring bulks are combined withbulk TFM cylinders, and the magnetic properties were investigated in detail during and after magnetization using stateof-the-art numerical simulations. A maximum value of Bz ·dBz /dz = −6040 T2 m−1 was obtained after conventional
FCM from Bapp = 10 T at 40 K for an HG-TFM with 10 mm
in inner diameter, which may be the highest value ever reported compared to any other magnetic sources. The mechanicalproperties of the HG-TFM were also investigated to propose arealistic configuration of the HG-TFM device reinforced by ametal support structure that is essential to prevent mechanicalfracture of the bulk superconducting material during the FCM
process due to its brittle, ceramic nature.

Figure 2. Magnetizing sequence for FCM of the HG-TFM, whichis the same as that for a conventional TFM. The external field, Bex ,is decreased linearly at a ramp rate of −0.222 T min−1 from
Bapp = 3, 5 or 10 T at a constant temperature at 40 K.

2. Numerical modeling procedure

inner diameter (I D) is assumed to be either 10, 20 or 36 mm
for both TFM components. The height (H) of the full-TFM
is 48 mm, for which three ring-shaped bulks 16 mm in H are
stacked, and each of the slit-TFMs are 16 mm in H. In themodel, the height of the full-TFM is determined so that thetrapped field capability to be 10 T for the HG-TFM with wider
I D = 36 mm and is fixed temporarily for the comparison withvarious I D cases. The number of layers of the full-TFM can be
reduced within the capability required in the device. Each bulk
is mounted separately in an Al-alloy ring 5 mm in thickness (OD = 70 mm, I D = 60 mm, H = 16 mm) adhered by a thin layerof epoxy resin. A thin indium sheet layer (0.1 or 1 mm in thickness) is inserted between each bulk to reproduce the boundary condition between each bulk in the realistic HG-TFM. A

Focusing on magnetic force applications for magnetic levitation [14–16], a higher magnetic field gradient product, Bz ·dBz /dz, is desirable in the system as indicated by equation (1).
The magnetic field gradient (dBz /dz) term should be highly
considered, as well as the trapped field (Bz ) term, to improvethe value of Bz · dBz /dz overall.
Figure 1(a) presents a cross-sectional schematic of thethree-dimensional numerical model of the HG-TFM, in whicha conventional ring-shaped TFM cylinder, labeled ‘full-TFM’,
is sandwiched by two TFM cylinders with slits 10 deg. wide in
the diagonal direction, labeled ‘slit-TFM’. Figures 1(b) and (c)show the top views of the full-TFM and slit-TFM, respectively.
The outer diameter (O D) of the HG-TFM is 60 mm and the3－ 140 －

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Table 1. Numerical fitting parameters for the assumed J c (B) characteristics of the GdBaCuO bulk used in equation (3), where the β value isadjusted to reproduce the experimental result for the trapped field [12].
T (K)
40

J c1 (A m−2 )3.5 × 109BL (T)
0.9

J c2 (A m−2 )2.7 × 10

9Bmax (T)

α

β

6.0

0.8

0.50

Figure 3. The time step dependence of the magnetic field, Bz , during FCM from Bapp = 3, 5 and 10 T at 40 K at the center of (a) the single
full-TFM (I D = 10 mm, O D = 60 mm, H = 48 mm) and (b) the single slit-TFM (I D = 10 mm, O D = 60 mm, H = 16 mm, slit 10 deg.
wide). The schematic view of the magnetic flux distribution and induced current direction in (c) the single full-TFM and (d) the single
slit-TFM.

solenoid coil of 170 mm in O D, 120 mm in I D and 200 mm
in H is used to apply the magnetic field for the magnetization
process (not shown in figure 1). As described earlier, appropriate mechanical reinforcement must be considered for the bulks
due to their brittle, ceramic nature for improving the reliability of the magnetization process and the device itself. Several studies have investigated the fracture behavior of the bulk
TFMs, which has a high risk of occurring under FCM fromapplied fields over 10 T at temperatures lower than 50 K, inparticular [17–19]. As shown in figure 1(a), the model represents a realistic experimental setup for the mechanical reinforcement of the bulk magnets, which will be performed in thenear future, employing outer Al-alloy rings and an outer SS
capsule of 5 mm in thickness that can provide a compressive
stress over −100 MPa when cooling from room temperature
to the operating temperature to perform FCM. The mechanicalreinforcement could endure up to Bapp = 10 T in actual FCM
experiments [20, 21].
Figure 2 presents the magnetizing sequence for FCM of the
HG-TFM, which is the same as that for a conventional TFM.
The external field, Bex , is decreased linearly at a ramp rateof −0.222 T min−1 . from Bapp = 3, 5 or 10 T at a constanttemperature at 40 K. Once the external field is ramped down

to 0 T for step 5, the static magnetic field 15 min later (forstep 8) is then referred to as the trapped field value, BT . Only
the z-component is considered for magnetic levitation because
gravity acts along the z direction. The electromagnetic phenomena of the bulk superconductor during the magnetization
process are analyzed using the commercial software, PhotoEDDY (Photon Ltd, Japan).
The nonlinear electrical property of the bulk superconductor is derived from the E–J power law as follows,
E = Ec

( )n
J
Jc

,

(2)

where Ec = 10−4 V m−1 is the characteristic electrical field,
n = 20 is an appropriate power-law exponent for GdBaCuO
bulk, and J c is the critical current density. The realistic J c (B)characteristics, including the fish-tail effect under certain magnetic fields, can be represented by the following equation proposed by Jirsa et al [22],
{
(
[ (
)
(
)α )]}B
B
Jc (B) = β · Jc1 exp − BBL + Jc2 Bmax
exp α1 1 − Bmax,
(3)4

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Figure 4. Numerical results for (a) the magnetic field, Bz , and (b) the magnetic field gradient product, Bz · dBz /dz, after magnetization with

Bapp = 10 T at 40 K along the z-axis inside the bulk annuli, comparing three types of TFMs: the HG-TFM, the HTFML and a conventionalring-shaped TFM (single full-TFM).

current state-of-the-art J c (B, T) characteristics [8]. The schematic view of the magnetic flux distribution and induced current direction in the single full-TFM is shown in figure 3(c),in which the conventional magnetic flux lines can be seen.
In the single slit-TFM case shown in figure 3(b), when Bex
decreased linearly, the Bz steeply decreased and became a negative value. Finally, the Bz value took a negative maximum atstep 5 and then slightly recovered to the final BT value becauseof the non-linear electrical property of bulk superconductor(see equation (2)). At step 8, BT = −2.8, −3.3, −3.6 T values
were obtained at the center of the single slit-TFM for Bapp = 3,
5 and 10 T, respectively. Figure 3(d) also shows the schematic view of the magnetic flux distribution and induced current direction in the single slit-TFM. An induced current flows
counterclockwise in each piece separated by the slits, which isthe same direction with the full-TFM. However, the downward(−z-direction) magnetic flux would penetrate through the slit
gap and exist even inside the central bore to build the magnetic loop in each piece of the slit-TFMs, which becomes the
opposite direction to that generated by the single full-TFM(+z-direction). The HG-TFM then provides a large magnetic
field gradient around the interface between the full-TFM withupward magnetic flux lines and the slit-TFM with downward
magnetic flux lines.
Figures 4(a) and (b), respectively, show a comparison of thenumerical results for the magnetic field, Bz , and the magnetic
field gradient product, Bz · dBz /dz, after magnetization with
Bapp = 10 T at 40 K along the z-axis inside the bulk annuli,
comparing three types of TFMs: the HG-TFM, the HTFML

where each relevant parameter, J c1 , BL , J c2 , Bmax , and α are
fitted from the experimental results for a GdBaCuO bulk reported by Kii et al [23]. The fitting coefficient, β, is employed so
as to modify the deviation from the actual trapped field value(obtained experimentally) after FCM, particularly at temperatures lower than 50 K [12]. The parameters assumed for the
GdBaCuO bulk material for equation (3) are summarized intable 1.

3. Electromagnetic analysis results
Before describing the mechanism of the HG-TFM in detail, theelectromagnetic properties of each key component of the HGTFM—the single full-TFM and the single slit-TFM—were
investigated. Figures 3(a) and (b), respectively, show the time
step dependence of the magnetic field, Bz , during FCM from
Bapp = 3, 5 and 10 T at 40 K at the center of the single fullTFM (I D = 10 mm, O D = 60 mm, H = 48 mm) and the single
slit-TFM (I D = 10 mm, O D = 60 mm, H = 16 mm, slit 10
deg. wide). For the single full-TFM case shown in figure 3(a),the final trapped field, BT , after FCM was almost equivalent toeach Bapp because of partial magnetization within the full capability of the full-TFM, which also enables the generation of
a comparatively homogeneous magnetic field inside the bulk
bore. Such a high field is realized by an induced supercurrent
flowing inside the full-TFM as depicted. Nowadays, it is estimated that the trapped field capability for a disk-shaped bulk pair
(O D = 24 mm, H = 24 mm) could be over 20 T, based on
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Figure 5. (a) The magnetic field, Bz , and (b) the magnetic field gradient product, Bz · dBz /dz, profiles of the HG-TFM with inner bores of

I D = 10, 20 and 36 mm along the z-direction inside the bulk bore after FCM from Bapp = 10 T at 40 K, compared with those of a single
full-TFM (−24 mm ⩽ z ⩽ 24 mm) and single slit-TFM pair (±z = 25 ∼ 41 mm).

and a conventional ring-shaped TFM (single full-TFM). The
dimensions of each TFM are shown in the figure, where thedimensions of the full-TFM part were assumed to be identicalfor each case (I D = 10 mm, O D = 60 mm, H = 48 mm).
The dimensions of the magnetic lens for the HTFML can bereferred to elsewhere [12]. In figure 4(a), the trapped field, Bz ,at the center (z = 0 mm) of the HG-TFM and full-TFM should
be comparable with the applied field of Bapp = 10 T. On theother hand, for the HTFML exploiting the diamagnetic lenseffect, Bz can be concentrated into the bulk annuli, in which aconcentrated trapped field of Bc = 11.0 T was achieved at 40 K
at z = 0 mm. In figure 4(b), the HG-TFM shows the highest
Bz · dBz /dz value of −6040 T2 m−1 at the boundary between
each TFM part, z = 24 mm, which is remarkably superior thanthe other two types of TFM. In this sense, to improve the magnetic force efficiently, it would be more desirable to control
the magnetic field gradient (dBz /dz) profile by focusing on thegradient itself rather than improving the trapped field (Bz ). One
significant advantage of the HG-TFM is that its superior magnetic properties could be realized using a conventional FCM
process at one temperature and without any additional costs,
except for the slit-TFM. Note again that figure 4 is an example
assuming a narrow 10 mm bore in inner diameter for each system. The magnetic properties of the HG-TFM would change
depending on the shape of the bulk material (O D, I D, H, slit
angle and so on) and the conditions of the magnetization process, such as the magnetizing temperature and Bapp .
Figures 5(a) and (b), respectively, show the magnetic field,
Bz , and the magnetic field gradient product, Bz · dBz /dz, profiles of the HG-TFM with inner bores of I D = 10, 20 and
36 mm along the z-direction inside the bulk bore after FCM
from Bapp = 10 T at 40 K, compared with those of a single
full-TFM (−24 mm ⩽ z ⩽ 24 mm) and single slit-TFM pair(±z = 25 ∼ 41 mm). In figure 5(a), the slit-TFM pair witha narrower bore of I D = 10 mm generates a higher negative
trapped field (= −3 T) over a wider area at ±z = 20 ∼ 40 mm,
which is effective for improving the HG-TFM performancewith a larger magnetic field gradient. The negative trappedfield of the single slit-TFM pair decreased with increasing
I D value and there is no remarkable negative value for
I D = 36 mm. On the other hand, for the cases of the full-TFM
and HG-TFM, the Bz profile becomes broad with increasing
I D value and the shape of the trapped field profile no longer
varies between the full-TFM and HG-TFM with I D = 36 mm.
Since Bz decays significantly with distance outside of the
TFM, i.e. at ±z ⩾ 24 mm, there is less, or no magnetic flux
controlled in the HG-TFM with wider I D = 36 mm.
In figure 5(b), for the HG-TFM, the peak value of Bz ·dBz /dz was enhanced with decreasing I D at the boundary
position between each TFM around ±z = 24 mm due to thepresence of the slit-TFM. A maximum Bz · dBz /dz value of
6040 T2 m−1 was achieved for I D = 10 mm, which is larger than that for the full-TFM (−3790 T2 m−1 ). It should
be noted that a Bz · dBz /dz value as large as −1400 T2 m−1along the +z-direction of the vertical magnet is required tolevitate a diamagnetic water drop in air [24]. In this sense,
the effective volume for magnetic levitation can be estimatedto be +z = 19–30, 17–30 and 13–27 mm inside the bore of
the HG-TFM with I D = 10, 20 and 36 mm, respectively.
For protein crystallization in a diamagnetic solution, a larger
Bz · dBz /dz value of −4450 T2 m−1 is required to realize anapparent zero-gravity condition without buoyancy flow, which
is much higher than that estimated numerically [25]. For realizing a higher field gradient product, the HG-TFM with a narrower inner bore is desirable, leading to a trade-off between
field gradient product and effective volume.
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Figure 6. (a) The final trapped field, BT (= Bz at step 8), at the center (x = y = z = 0) and (b) the maximum field gradient product,|Bz · dBz /dz|, at the boundary position between the full and slit-TFMs of the HG-TFM, as a function of Bapp for various I D cases. The
results are compared to that of the full-TFM cases and other large-scale magnets: superconducting magnets (SM), and hybrid-type
superconducting magnets (HM).

Figures 6(a) and (b) summarize the final trapped field, BT(= Bz at step 8), at the center (x = y = z = 0) and the maximum
field gradient product, |Bz · dBz /dz|, around the boundary position between the full and slit-TFMs of the HG-TFM, as a function of Bapp for various I D cases. The results for the full-TFM
cases are also shown for reference. In figure 6(a), the trappedfield capability is equivalent for all cases; thus, the relation
BT = Bapp , is established based on the typical FCM process.
However, for the magnetic field gradient product shown infigure 6(b), the HG-TFM would work more effectively for
Bapp higher than 5 T and for narrower bores smaller thanI D = 20 mm compared to the full-TFM. Table 2 summarizes
the maxima of the magnetic properties for each case including
the HG-TFM, HTFML and full-TFM, extracted from figures 4
and 6. The HG-TFM with I D = 10 mm would provide amaximum |Bz · dBz /dz| = 6040 T m−2 when BT = 10 T
at 40 K, which may be the record-high value compared tothat of other large-scale magnets: SM ∼ 1500 T m−2 , andHM ∼ 3000 T m−2 using liquid helium, shown in figure 6(b)[4, 26].
In most related studies, based on apparatus using a permanent magnet with a magnetic field ∼1 T, the magnetoArchimedes method must be exploited to reduce the requiredmagnetic force using a paramagnetic medium solution[27, 28]. The HG-TFM no longer needs such a method,and consequently, can provide simpler, medium-free operation with air or water. These advantages of the HG-TFM
can provide the versatility of a quasi-zero gravity space asa desktop-type magnetic source for magnetic levitation processing, which enables the suppression of gravity-induced
convection in a wide range of potential industrial applications
such as protein crystallization and cell culture [1, 2]. It should
be noted that Bz · dBz /dz values of 1980 and 2760 T2 m−1 canbe achieved after FCM from Bapp = 10 T even for the single
full-TFM with I D = 36 and 20 mm (without the slit-TFM),
respectively, as shown in table 2, which are higher than that
achieved by SMs [4]. These results suggest that the single fullTFM can be also applicable for quasi-zero gravity in the open

space outside the vacuum chamber with a range of 15–30 mm
in diameter. There is a limit for the enlargement of the space inthe bore because it is difficult to fabricate good quality bulks>60 mm in O D, resulting in a narrower bore compared to thatof SMs.
In our previous work [12], where the mechanism of magnetic levitation in the quasi-zero gravity space is explained indetail, it was highlighted that a large magnetic field gradientproduct up to 3000 T2 m−1 of that particular HTFML design
could be highly applicable to magnetic separation. Regarding the effectiveness of the magnetic force for crystal growth,
it is shown elsewhere that the magnetic force affects several
features: the magnetic field orientation, convection control,
reduction of sedimentation and so on [14]. However, there
are no theoretical rules yet regarding how the magnetic force
works during the process and it differs between the target
materials used. Thus, appropriate design of the I D of the HGTFM needs to be explored as related to the particular application, where the magnetic force profile in the HG-TFM could
be correlated with the quality of the resultant crystallization.

4. Mechanical stress analysis results
The mechanical fracture of bulk superconductors has beenreported in several studies, where a crack might occur along
the circumferential direction mainly due to the hoop stressinduced during FCM from applied fields over 10 T at temperatures below 50 K [17–19]. To date, to prevent such mechanical fracture during magnetization, mechanical reinforcement has been usefully applied using glass fiber reinforced
epoxy resin [29] or shrink-fit steel [7]. We also proposed a new
hat structure of an outer metal reinforcement ring based on
the results of mechanical stress simulations, in which a large(RE)BaCuO ring-shaped bulk (I D = 36 mm, O D = 60 mm,
H = 20 mm) was experimentally confirmed to endure FCM
from 10 T without fracture [20]. For the HTFML consisting of a (RE)BaCuO lens and (RE)BaCuO TFM cylinder,
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Table 2. Numerical results of maxima of the magnetic properties for each case including the HG-TFM, HTFML and full-TFM magnetizedat 40 K, extracted from figures 4 and 6.

HG-TFM
Bulk I D (mm)Bz (Bapp ) (T)|Bz ·dBz /dz| (T2 m−1 )(single full-TFM)
Magnetization
Temperature (K)10
10 (10)6040 (3790)

HTFML
20
10 (10)3460 (2760)36
9.8 (10)1980 (1850)1011 (10)2430 (1850)

FCM
40

ZFCM + FCM

Table 3. Assumed mechanical parameters (EY :Young’s modulus

the mechanical properties have been analyzed during themagnetizing process from Bapp = 10 T [30], in which thenecessity of adequate mechanical reinforcement was strongly
suggested, at least for the GdBaCuO TFM cylinder, but possibly the magnetic lens as well. It is also necessary to investigate the mechanical properties of the present HG-TFM as wellduring FCM, where the full-TFM part is tightly sandwichedby the slit-TFM pair.
After calculating the trapped field profile shown in the previous section, the nodal force was then imported into anothersoftware package, Photo-ELAS (Photon Ltd., Japan), for calculating the electromagnetic stress on each mesh element of
the bulk TFMs during magnetization, which enables us toassess the reliability of the HG-TFM in terms of the mechanical reinforcement method.
Elastic behavior in an isotropic material can be expressedby Hooke’s law, in which the stress tensor, σij , is linearly proportional to the strain tensor, εij , as follows
σij = λ · εkk · δij + 2G · εij ,

(4)

E·ν
λ = (1+ν)(1−2ν) ,

(5)

G = 2(1E+ν) ,(6)and ν: Poisson ratio) for numerical stress analysis of the HG-TFM
shown in figure 1 [20, 31].

(RE)BaCuO bulk
Epoxy resin
Al alloy (A7075-T6)
Indium
SS 304EY (GPa)

ν

100
3.0
78
12.7
193

0.33
0.37
0.34
0.45
0.28

main component of the electromagnetic stress results from thehoop stress along the y-direction in the full-TFM part. The
maximum σYY value was almost independent of the bore size
because the trapped field is equivalent for each HG-TFM withdifferent bore sizes as shown in figure 6(a). These numericalresults for the stress profile are similar to that reported for theannular (RE)BaCuO bulk magnet system (full-TFM) for an
NMR spectrometer [21], in which an electromagnetic hoop
stress about 100 MPa was generated at the inner peripheral
region of the annular bulks reinforced by a similar structure.
This means that the present reinforcement technique would
work even for the present HG-TFM system. Considering thecompressive stress of −100 MPa from the reinforcement by
the Al-alloy rings and the SS capsule during the cooling process before FCM, the maximum total stress would be less than
the fracture strength of typical Ag-doped (RE)BaCuO bulks
of 50–70 MPa [32]. As a result, the full-TFM part should beappropriately reinforced and not break [21].
Figures 8(a)–(c) show the contour map of the Von Mises
stress, σVM , the electromagnetic hoop stress along the ydirection, σYY , and the electromagnetic radial stress along thex-direction, σXX , respectively, for the slit-TFM pair of the HGTFM with inner diameters of I D = 10, 20 and 36 mm, justafter FCM from 10 T. For the case of I D = 10 mm, a maximum Von Mises stress of σVM = 54 MPa exists at the surfaces of the slit-TFM pair facing the full-TFM part. The σXX
profile for each I D, as shown in figure 8(c), is similar tothat for σVM . On the other hand, the σYY contribution to the
Von Mises stress, as shown in figure 8(b), is relatively small.
These results suggest that the main component of the electromagnetic stress results from the electromagnetic radial stressalong the x-direction, σXX , in the case of I D = 10 mm andI D = 20 mm. However, for the wider I D = 36 mm, the electromagnetic stress mainly results from the hoop stress along they-direction, σYY . Since an induced current flows in two regions

where λ and G represent Lame’s constants, δij is the Kronecker
delta function, EY is the Young’s modulus, and ν is the Poisson ratio. The mechanical parameters, EY and ν, for each component of the HG-TFM are summarized in table 3, which areassumed in the simulation to be isotropic and in the elastic
region. Note that all components, including the epoxy resin,
indium and air gap, as shown in figure 1, were included in themodeling of the HG-TFM, which should be considered for theaccurate prediction of the mechanical behavior [31].
Figures 7(a) and (b) show a contour map of the Von Mises
stress, σVM , and the electromagnetic hoop stress along the ydirection, σYY , respectively, calculated for the full-TFM partof the HG-TFM with inner diameters of I D = 10, 20 and
36 mm, just after FCM from 10 T (step 5). In figure 7(a),the σVM value, which is a scalar quantity, represents the total
value of the mechanical stresses including all directions. Compared with the maximum σYY value shown in figure 7(b), which
is close to the maximum σVM value of 90 MPa around theinner periphery of the full-TFM part, it was found that the8－ 145 －

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Figure 7. Contour map of (a) the Von Mises stress, σVM , and (b) the electromagnetic hoop stress along the y-direction, σYY , calculated forthe full-TFM part of the HG-TFM with inner diameters of I D = 10, 20 and 36 mm, at step 5 just after FCM from 10 T.

Figure 8. Contour map of (a) the Von Mises stress, σVM , (b) the electromagnetic hoop stress along the y-direction, σYY , and (c) the
electromagnetic radial stress along the x-direction, σXX , for the slit-TFM pair of the HG-TFM with inner diameters of I D = 10, 20 and
36 mm, just after FCM from 10 T.

in the slit-TFM independently due to the existence of slits, theresultant trapped field and the mechanical stress become lower,
compared to the full-TFM, even if the slit-TFM is magnetizedby FCM from 10 T.

During the magnetization of the HG-TFM exploiting slitTFMs stacked on the full-TFM, an extra stress component
may be generated due to the repulsive force between each
TFM part. Figure 9(a) shows a cross-sectional contour map
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Figure 9. (a) Cross-sectional contour map of the electromagnetic stress along the vertical direction, σZZ , for the HG-TFM with various
inner diameters, just after the FCM process from 10 T. (b) The σZZ distribution along the z-direction at the inner periphery (x = 18 mm) andat the outer periphery (x = 30 mm) for the HG-TFM with I D = 36 mm, extracted from (a).

of the electromagnetic stress along the vertical direction, σZZ ,for the HG-TFM with various inner diameters, just after the
FCM process from 10 T. The positive σZZ value is concentrated mainly in the inner periphery of the slit-TFM facing thefull-TFM, and the magnitude of σZZ increases with increasing
I D These results suggest that a repulsive force exists in thisregion. However, the positive σZZ region vanishes at the outerinterface of the slit-TFM facing the full-TFM (z = ±24 mm,−15 ⩽ x ⩽ 30 mm for I D = 36 mm case), which indicatesthe possibility of an attractive force or very small repulsive
force there. Figure 9(b) shows the σZZ distribution along thez-direction at the inner periphery (x = 18 mm) and at the outer
periphery (x = 30 mm) for the HG-TFM with I D = 36 mm,
which were extracted from figure 9(a). At the inner periphery,the σZZ value changes from positive to negative around theinterface (z = ±24 mm). These results indicate that a repulsive force exists at the inner interface. On the other hand, atthe outer periphery, the σZZ value is negative and continuous

for both the slit-TFM and full-TFM, suggesting that an attractive magnetic force might exist at the outer interface. Similar
trends were also observed for the HG-TFM for I Ds = 10 and
20 mm.
Figure 10(b) shows a contour map of the final trapped field,
BT , of the HG-TFM with I D = 20 mm after FCM from 10 T.
It should be noted that a trapped field along the +z-direction
exists at the periphery of the slit-TFM (region A), which has asimilar BT strength of 10 T as for the full-TFM. These results
suggest that ‘region A’ is magnetically attracted to the magnetized full-TFM. On the other hand, there exists little fieldtrapped downward along the z-direction in the inner periphery
region of the slit-TFM (‘region B’). These results indicate thata repulsive magnetic force exists in the counter side in the fullTFM, which can be understood well from the schematic viewof the magnetic flux lines in figure 10(a).
Figure 10(a) shows a schematic view of the magnetic
flux profile for the HG-TFM after FCM. To understand the10－ 147 －

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Figure 10. (a) Schematic view of the magnetic flux profile for the HG-TFM after FCM. (b) Contour map of the final trapped field, BT , ofthe HG-TFM with I D = 20 mm after FCM from 10 T. (c) The effective magnetic poles of the HG-TFM after FCM. The outer periphery
region (region A) and inner periphery region (region B) of the slit-TFM can be considered as opposing magnetic poles.

distribution of the magnetic flux lines at the interface visually,
the full-TFM and the slit-TFM pair are placed at a distance.
It can be confirmed visually that the magnetic flux lines coexist at the interface and form the superposition of the magnetic fields that is destructive around the central bore or constructive around the bulk periphery.
Let us describe these results using a magnetic pole model.
Figure 10(c) shows the effective magnetic poles of the HGTFM after FCM, which presents the mechanism of the larger
magnetic gradient of the HG-TFM. The outer periphery region(region A) and inner periphery region (region B) of the slitTFM can be considered as opposing magnetic poles. As a result, region A is attractive (an N–S or S–N pair) and region B
is repulsive (N–N or S–S pair) with respect to the magnetizedfull-TFM at the interface. Since both TFM parts are mounted
in an Al-alloy ring and the whole HG-TFM is encapsulated
in an SS capsule, σZZ acts as a compressive stress, and thatmaxima is around 50 MPa for the full-TFM and 35 MPa forslit-TFM in the HG-TFM with I D = 36 mm. However, in the
narrower bore cases, I D = 10 and 20 mm, σZZ decreases despite the superior Bz · dBz /dz performance. In any case, there
is little fracture risk due to the compressive stress for the HGTFM during FCM from 10 T, since the compressive fracture
strength of (RE)BaCuO bulk is about one order of magnitude
higher than the tensile mechanical strength [33].

quasi-zero gravity space using magnetic force, in which a slit
ring bulk (slit-TFM) was tightly stacked with a TFM cylinder(full-TFM). State-of-the-art numerical simulations were used
to investigate the magnetic and mechanical properties detailduring and after magnetization. The important results and conclusions in this study are summarized as follows.
(a) A maximum value of the magnetic field gradient productof Bz · dBz /dz = −6040 T2 m−1 was obtained after conventional FCM from Bapp = 10 T of the HG-TFM witha 60 mm outer diameter and 10 mm inner diameter. Thisvalue may be the highest ever reported compared to any
other magnetic sources. The superiority of the HG-TFM
is the easier magnetization process including a single temperature and a simpler construction without any additionalcost, but also the higher Bz · dBz /dz can be provided in an
open space outside the vacuum chamber.
(b) The Bz · dBz /dz value increased with decreasing inner diameter of the HG-TFM and with increasing applied field,
Bapp , during FCM. Even if the inner diameter of the HGTFM is 36 mm, a Bz · dBz /dz value of 1980 T2 m−1 can beachieved, which is slightly higher than 1850 T2 m−1 forthe single full-TFM case.
(c) The electromagnetic stress during the FCM process was
also investigated to analyze the mechanical behavior
of HG-TFM device. The electromagnetic stress in the
HG-TFM device during the FCM process mainly resultsfrom the hoop stress along the y-direction, σYY , for the fullTFM.
(d) The outer and inner periphery regions of the slit-TFM
can be considered as opposing magnetic poles. The outer

5. Conclusion
We have proposed a new concept of a HG-TFM. The HG-TFM
is made from (RE)BaCuO bulk superconductors to realize a
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K Takahashi et al

periphery region is attractive (N–S or S–N pair) and theinner periphery region is repulsive (N–N or S–S pair) withrespect to the magnetized full-TFM at the interface. However, it was confirmed that there is little fracture risk forthe bulks during FCM from 10 T in the proposed realistic configuration of the HG-TFM, where both TFM parts
are mounted in Al-alloy rings and the whole HG-TFM is
encapsulated in an SS capsule.
(e) A quasi-zero gravity space can be realized using the HGTFM with its large Bz · dBz /dz value in an open spaceoutside the vacuum chamber even without the magnetoArchimedes method. The HG-TFM device is a compact
and cryogen-free desktop-type magnetic source to provide
a large magnetic force and can be applicable to scientificresearch, such as in the life/medical sciences for protein
crystallization and cell culture.

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Acknowledgments
This research is supported by JSPS KAKENHI Grant No.
19K05240 and by Adaptable and Seamless Technology transfer Program through Target-driven R&D (A-STEP) fromJapan Science and Technology Agency (JST), Grant Nos.
VP30218088419 and JPMJTM20AK. M D Ainslie would liketo acknowledge financial support from an Engineering andPhysical Sciences Research Council (EPSRC) Early Career
Fellowship, EP/P020313/1. All data are provided in full in the
results section of this paper.
ORCID iDs
Keita Takahashi  https://orcid.org/0000-0002-8278-2688
Hiroyuki Fujishiro  https://orcid.org/0000-0003-1483835X
Mark D Ainslie  https://orcid.org/0000-0003-0466-3680
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10. (H-9) K. Takahashi, H. Fujishiro, S. Namba and M. D. Ainslie,“Experimental realization of an all-(RE)BaCuO hybrid trapped field magnet lens
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