bluuebunny/crossref_metadata_2025 huggingface dataset:
Diamagnetie Shielding and Meissner Effect in the High Tc Superconductor SrxLa2-xCuO4-y
Authors: Tokumoto Madoka , Ihara Hideo , Murata Keizo , Hirabayashi Masayuki , Terada Norio , Senzaki Kiyoshi , Kimura Yoichi
Published: November 2005

Static magnetization measurements of the high T
c superconductor Sr
x
La2-x
CuO4-y
, with the layered perovskite K2NiF4 structure and a 43 K resistive onset, are reported. Diamagnetic susceptivility was observed below 37 K indicating a bulk superconductivity. The magnetization measurement revealed a characteristic nature of type-II superconductor with H
c1(0)≈500 Oe and H
c2(0)>100 kOe.
Josephson Junctions Observed in La1.8Sr0.2CuO4 Superconducting Polycrystalline-Films
Authors: Moriwaki Kazuyuki , Enomoto Youichi , Murakami Toshiaki
Published: November 2005

La0.8Sr0.2CuO4 (LSC) superconducting polycrystalline films with onset T
c of 32 K are fabricated using the sputtering method. By observing current voltage curves, the (100)-plane films are found to contain weak-link type Josephson-junctions in the film. The electrical resistivity and the maximum DC Josephson current in the films are also measured. Origins of the observed Josephson-junctions are discussed and compared with that of BaPb(1-x)Bi(x)O3. The LSC polycrystalline films are expected to be more useful than BPB films because of their higher T
c.
The Importance of the Positively Charged Surface for the Epitaxial Growth of Diamonds at Low Pressure
Authors: Tsuda Minoru , Nakajima Mitsuo , Oikawa Setsuko
Published: November 2005

The mechanism of the propagation of the epitaxial growth of diamonds at low pressure was investigated in terms of quantum chemistry. The reactions for diamond structure formation proceed simultaneously at many points on the surface of a diamond, and the epitaxial growth continues so long as methyl radicals are supplied. The most important requirement is the maintaining of positive charges on the growing surface.
Temperature Dependence of Electrical Properties of Nitrogen-Doped 3C-SiC
Authors: Yamanaka Mitsugu , Daimon Hiroshi , Sakuma Eiichiro , Misawa Shunji , Endo Kazuhiro , Yoshida Sadafumi
Published: November 2005

The electrical properties of nitrogen-doped n-type 3C-SiC layers, epitaxially grown on Si by chemical vapor deposition, have been investigated at temperatures ranging from 10 to 1000 K. The activation energy of the N-donors was obtained from the temperature dependence of carrier density. The donor-density dependence of the activation energies of donors in N-doped 3C-SiC is quite different from that of unintentionally-doped ones, and the donors in unintentionally-doped 3C-SiC were proved not to be nitrogen atoms.
Modification of Diacetylene LB Films by Acid and Basic Vapor Treatments before Polymerization
Authors: Saito Kazuhiro , Saito Mitsuyoshi , Ikegami Keiichi , Kuroda Shin-ichi , Sugi Michio
Published: November 2005

Exposure of diacetylene LB films to the vapor from hydrochloric acid or ammonia water before polymerization has been found to increase the absorbance due to the polymer formed by UV irradiation. It is suggested that these treatments rearrange the monomer molecules which enhances the yeild of polymerization. For the acid-treated case, the absorbance amounts to about three times as large as those of conventionally polymerized films.
Effects of Annealing on ZnS:Tb, F Electroluminescent Thin Films Prepared by rf Magnetron Sputtering
Authors: Mita Juro , Koizumi Masumi , Kanno Hiromasa , Hayashi Tadashi , Sekido Yoshihiro , Abiko Ichimatsu , Nihei Kohji
Published: November 2005

The effects of annealing on sputtered ZnS:Tb, F thin films is investigated by electron probe microanalysis, secondary ion mass spectroscopy and X-ray photoelectron spectroscopy. It is shown that the annealing decreases the F/Tb atomic ratio from 4 to 1, due to the release of F atoms. It is concluded that many of the F ions not contributing to the formation of luminescent centers with Tb ions exist in as-sputtered film and that efficient Tb-F complex centers are formed by annealing at over 400°C. Luminance is enhanced by increasing the Tb-F complex centers and decreasing the hot-electron scattering centers of the F ions.
Motion of a Pulse Intense Ion Beam in a Sector Torus Magnetic Field
Authors: Nakagawa Yoshiro , Matsukawa Yoshinobu , Enomoto Tamotsu , Ariyoshi Takeshi , Tsutsumi Shiro
Published: November 2005

A long-pulse-intense ion beam (protons. ∼3 kA, ∼50 keV, ∼400 ns) was projected along the magnetic field line into a sector torus with a straight section (90° sector, 37.5 cm torus radius, 9.4 cm chamber diameter). The motion of the intense ion beam was measured by damage paper and a biased ion collector. A large part of the ion beam was transported through the sector torus when a magnetic field of 0.8 T was applied. The motion of the pulse intense ion beam could be approximated by calculations involving the motion of a single particle in a toroidal magnetic field.
Preliminary Results of Vacuum Pressure Measurement by Laser Ionization Method
Authors: Ichimura Shingo , Kokubun Kiyohide , Shimizu Hazime
Published: November 2005

The possibility of vacuum pressure measurement by ionizing gaseous atoms or molecules with laser radiation was studied. Xe ions were successfully detected after irradiation by a focused Xe-Cl excimer laser, indicating that non-resonant 4 photon ionization was realized with the present system. It was confirmed that Xe signal intensity, as measured by a quadrapole mass analyzer, changed in proportion to Xe gas pressure from 10-5 Torr to 10-9 Torr. Xe isotopes were also measured and the results correlated well with their natural abundance.
Raman Study of Misfit Strain and Its Relaxation in ZnSe Layers Grown on GaAs Substrates
Authors: Matsumoto Takashi , Kato Takamasa , Hosoki Mitsuru , Ishida Tetsuro
Published: November 2005

Raman spectra are measured on ZnSe epitaxial layers with a thickness of 0.09∼3.4 µm grown on GaAs(100) substrates by low-pressure vapor phase epitaxy both in RF hydrogen plasma and in plasma-free conditions. A 1 cm-1 high-frequency shift is observed in the longitudinal optical (LO) Raman peak for layers thinner than 0.2 µm grown in the plasma-free condition. The shift is due to the two-dimensional elastic strain in epitaxial layers. No frequency shift is observed for layers grown in hydrogen plasma, even for the thinnest layer. The LO phonon scattering efficiency depends on the distance from layer-substrate interface.
Electric Field-Induced Absorption in GaInAsP/InP MQW Structures Grown by LPE
Authors: Ohki Yoshimasa , Shimomura Kazuhiko , Kikugawa Tomoyuki , Ravikumar K. G. , Izumi Akira , Arai Shigehisa , Suematsu Yasuharu
Published: November 2005

The absorption spectrum induced by applying an electric field was measured for GaInAsP/InP MQW structures with the corresponding bandgap wavelength λg∼1.3 µm. A 25-pairs MQW wafer was grown by LPE technique with a well width L
z=150 Å, and a barrier width L
b=200 Å. The maximum electro-absorption in this waveguide structure was observed to be 550 cm-1 at an applied voltage of 25 V. From this value, the refractive index variation in the quantum well layer was estimated as 0.27%.
On an Appearance of Steps in the I-V Characteristics of Sb Doped Si near the Metal-Nonmetal Transition
Authors: Ochiai Yuichi , Matsuura Etsuyuki
Published: November 2005

We have observed the existence at low temperatures of several steps in the I-V characteristics of nonmetallic Sb doped Si near the metal-nonmetal transition. The steps appear at equal intervals in the bias voltage of the I-V curve and the intervals in the voltage are independent of magnetic field. Such strongly nonlinear conduction can be explained by neither the Josephson junction effect nor the Stark ladder effect. In order to clarify the physical origin of this nonlinear conduction, we have compared it with tunneling models according to which the intervals of the step are considered to be independent of the magnetic field.
Stable Single-Longitudinal-Mode Operation over Wide Temperature Range on Semiconductor Lasers with a Short External Cavity
Authors: Kawanishi Hidenori , Hayashi Hiroshi , Yamamoto Osamu , Miyauchi Nobuyuki , Maei Shigeki , Yamamoto Saburo , Hijikata Toshiki
Published: November 2005

V-channeled Substrate Inner Stripe lasers coupled with a Short External Cavity maintain one single longitudinal mode over wide temperature ranges without mode hopping. Temperature stability is obtained when the thermal shift of the modulated spectrum envelope coincides with that of the longitudinal modes. We enhanced the stability by using a Si submount in place of a Cu submount for the laser. The temperature dependence of the gain maximum is compensated by the small thermal expansion of Si. The laser shows a longitudinal mode locking range of more than 46°C. The data are consistent with theoretical calculations.
Wall Energy and Exchange Stiffness in CoCr Films Sputtered on Low Temperature Substrates
Authors: Honda Shigeo , Takahashi Kenichi , Kusuda Tetsuzo
Published: November 2005

In CoCr films sputtered on polyimide substrates with 27°C, the stripe domains and the wall motion could be observed clearly using the Bitter method. The behaviour of the domains and the magnetic properties, the saturation magnetization M
s, Curie temperature T
c and the anisotropy energy K
u were investigated as a function of Cr-content. Due to the dilution effect, the values of M
s, T
c and K
u decrease with increasing Cr-content. The wall energy density and the exchange stiffness change with M
s
2, namely they decrease with Cr-content, while the wall width is about 210 Å independent of Cr-content.
Effect of in situ Thermal Annealing on Crystalline Quality of Ge Layers Grown by Molecular Beam Epitaxy on Si (100)
Authors: Fukuda Yukio , Kohama Yoshitaka
Published: November 2005

Recent studies have shown that the crystalline quality of the Ge layers grown on Si substrates by molecular beam epitaxy (MBE) can be improved by thermal annealing during their deposition. In order to investigate the effect of the thermal annealing, the Ge/Si interfaces of samples grown under a variety of conditions have been studied with transmission electron microscopy (TEM). The TEM results revealed that the relaxation process of the lattice mismatch between the Ge and the Si was not straightforward. The dislocations generated during the Ge deposition were irregularly distributed in the Ge layer, and were changed into a regular array of misfit dislocations lying on the Ge/Si interface by the thermal annealing.
Preparation of High Tc Superconducting (La1-xSrx)2CuO4
Authors: Nishihara Takaharu , Takata Masasuke , Yamashita Tsutomu
Published: November 2005

Mixing process in the preparation of high T
c superconducting La1.8Sr0.2CuO4 was evaluated. Solution mixing by nitric acid was found to be effective in producing a homogeneous superconductor.
Crystal Structure of a Ba-Y-Cu-O Superconductor as Revealed by Rietveld Analysis of X-Ray Powder Diffraction Data
Authors: Izumi Fujio , Asano Hajime , Ishigaki Tōru , Ono Akira , Okamura Fujio P.
Published: November 2005

The crystal structure of a Ba-Y-Cu-O superconductor was refined by the Rietveld analysis of X-ray powder diffraction data. This material is orthorhombic with lattice parameters a = 3.8845 Å, b = 3.8293 Å, and c = 11.6926 Å. Possible space groups are P222, Pmm2, and Pmmm. Metal atoms have essentially the same configuration as that in the perovskite-type structure. A structural model is proposed in which an oxygen atom at (0, 0, 1/2) is deficient.
High Tc Superconductivity in Tm-Ba-Cu-O System
Authors: Kanbe Shinsaku , Hasegawa Tetsuya , Aoki Makoto , Nakamura Takashi , Koinuma Hideomi , Kishio Kohji , Kitazawa Koichi , Takagi Hidenori , Uchida Shin-ichi , Tanaka Shoji , Fueki Kazuo
Published: November 2005

The oxide system Tm1-x
Ba
x
CuO
y
was found to exhibit the superconducting transition temperature above 90 K for the nominal compositions with x=0.6-0.8. The single phase composition was obtained for the specimens around x=0.7. The crystal structure was to be an oxygen deficient perovskite structure reported for a Y-Ba-Cu-O system.
X-Ray and Electron-Microscopic Studies on Single-Phase High Tc Superconductor, YBa2Cu3Oy
Authors: Takayama-Muromachi Eiji , Uchida Yoshishige , Matsui Yoshio , Kato Katsuo
Published: November 2005

High T
c superconductor in the system Y-Ba-Cu-O was obtained as a single phase. Its composition was determined to be YBa2Cu3O
y
. The compound is practically stoichiometric in regard to the Y-Ba-Cu ratio, the homogeneity range regarding the Y/Ba ratio, if any, being very small. The lattice image of the compound obtained by electron microscopy showed clearly that 3-c structure comes from the ordering of Y and Ba ions located in the A-site of perovskite-related structure.
Superconductivity above 90 K in Y-Ba-Cu-O Compounds and Their Critical Current Densities at 77 K
Authors: Matsuzaki Kunio , Inoue Akihisa , Kimura Hisamichi , Moroishi Keiji , Masumoto Tsuyoshi
Published: November 2005

Y0.4Ba0.6Cu1O3-y
was found to consist of a mostly single orthorhombic phase and exhibit superconductivity with onset at 93 K, midpoint at 92 K and zero resistance (offset) at 90 K. As the ratio of Y0.4Ba0.6 to Cu increases from 1.0 to 2.0, the volume fraction of other unidentified phases increases and the offset T
c decreases to below 77 K at 2.0 through 85 K at 1.5, even though the high onset T
c remains constant. Critical current densities at 77 K and zero applied field for the Y-Ba-Cu oxides are as low as about 10 A/cm2 and hence the high T
c oxides are concluded to be an extremely soft superconductor.
AC Josephson Effect in Point-Contacts of Ba-Y-Cu-O Ceramics
Authors: Yamashita Tsutomu , Kawakami Akira , Nishihara Takaharu , Hirotsu Yoshihiko , Takata Masasuke
Published: November 2005

Clear Shapiro-steps were observed in I-V curves of point-contact Josephson junctions fabricated by BaYCuO ceramics. The observed voltage step is just equal to applied frequency times (h/2e), where h and e are, respectively, the Planck constant and electron charge.
Tunneling Spectroscopy of Y-Ba-Cu-O Compound
Authors: Iguchi Ienari , Watanabe Hirohito , Kasai Yuji , Mochiku Takashi , Sugishita Akimitsu , Yamaka Eiso
Published: November 2005

Single particle tunneling between a sintered Y-Ba-Cu-O compound and a Pb film is presented. The differential tunnel characteristic as a function of junction voltage exhibits a series of gap structure at Δ, 2Δ and 3Δ. The observed value of 2Δ/k
B
T
c is 10.5, much greater than the BCS value of 3.52. Temperature dependence of the gap is in good agreement with the BCS theory.
Rietveld Refinement of the Structure of Ba2YCu3O7-x with Neutron Powder Diffraction Data
Authors: Izumi Fujio , Asano Hajime , Ishigaki Tōru , Takayama-Muromachi Eiji , Uchida Yoshishige , Watanabe Noboru , Nishikawa Tetsuji
Published: November 2005

The crystal structure of a high T
c superconductor, Ba2YCu3O7-x
, has been refined by the Rietveld analysis of TOF neutron powder diffraction data. Two polymorphs of Ba2YCu3O7-x
are contained in the sample: orthorhombic (74%) and tetragonal (26%) forms. The two forms have nearly the same structure closely related to that of perovskite-type compounds. In the orthorhombic form, the occupation factor of an oxygen atom on the a axis differed greatly from that on the b axis, which is the main reason why Ba2YCu3O7-x
crystallizes in the orthorhombic form.
Surface Potential Decay and Residual Voltage Measurements in Highly Elongated Polyethylene
Authors: Park Dae Hee , Kyokane Jun , Yoshino Katsumi
Published: November 2005

The residual voltage which appears in a pre-stressed polyethylene film is found to increase with increasing draw ratio and then to decrease again at higher draw ratio. On the other hand, the ratio of a surface potential decay decreases with increasing draw ratio and then again increases at higher ratio. These results are discussed in terms of the change of the carrier transport process, localized state density and carrier mobility.
Magnetization Measurements in Y-Ba-Cu-O Compound System
Authors: Kumakura Hiroaki , Togano Kazumasa , Fukutomi Masao , Uehara Mitsuru , Tachikawa Kyoji
Published: November 2005

Magnetization measurements for (Y0.5Ba0.5)CuO3-y
compound at 77 K and 4.2 K indicated that the material was type II superconductor. Critical current densities at 1 T derived from magnetization curves were 13 A/cm2 at 77 K and 3×103A/cm2 at 4.2 K. Upper critical field H
c2(mid-point) at 77 K was 15 T. Several parameters such as H
c2 at 0 K, H
c, ζGL, λGL and κ were estimated.
Crystal Structure of Superconductor Ba2YCu2.89O6.80
Authors: Sato Shoichi , Nakada Ichiroh , Kohara Takao , Oda Yasukage
Published: November 2005

Crystal structure of Ba2YCu2.89O6.80 sigle crystal was determined by the X-ray diffraction method at room temperature. The space group is Pmmm with lattice parameters a = 3.8699(8) Å, b = 3.8667(8) Å and c = 11.688(2) Å. A specific structure was found in the c-plane sandwiched between two barium layers. The Cu-O bond perpendicular to the plane 1.828(6) Å is shorter than the normal bond 1.95 Å. Within the plane oxygen atoms show an extremely large thermal vibration.
Rf Power Dependence of AC Josephson Current in Point-Contacts of BaY(Tm)CuO Ceramics
Authors: Yamashita Tsutomu , Kawakami Akira , Nishihara Takaharu , Takata Masasuke , Kishio Kohji
Published: November 2005

Using BaYCuO and BaTmCuO ceramics, point-contact Josephson junctions were fabricated to observe ac Josephson effect. Clear Shapiro steps were observed at 4.2 K. The rf power dependence of Josephson currents were qualitatively fitted to Bessel functions.
Single Crystal Growth of Layered Perovskite Metal Oxides
Authors: Hasegawa Haruhiro , Kawabe Ushio , Aita Toshiyuki , Ishiba Tsutomu
Published: November 2005

(La, Sr)2CuO4 single crystals were grown in a molten copper oxide flux at a relatively low temperature, and their habit planes were examined by X-ray Laue patterns.
Analysis of Astigmatism in High-Power Semiconductor Lasers
Authors: Ohtoshi Tsukuru , Yamaguchi Ken , Chinone Naoki
Published: November 2005

A beam profile near the facet of high-power semiconductor lasers is precisely analyzed using two-dimensional computer simulation. Astigmatism and its optical-power dependence can be accurately predicted in this way. Lasers with effective three-layer stab waveguides (i.e. single-step-index waveguides) in the lateral direction have two beam waists. That is, they have a rather large astigmatic distance that depends on the power. To realize high-power lasers with a small astigmatic distance that is relatively independent of output power, waveguides with a graded-index profile or multi-step-index profile are needed.
Characterization of the High Tc Superconductor (Ba0.7Y0.3)CuO3-δ
Authors: Nakazawa Yasuhiro , Ishikawa Masayasu , Takabatake Toshiro , Takeya Hiroyuki , Shibuya Takashi , Terakura Kiyoyuki , Takei Fumihiko
Published: November 2005

By establishing a partial phase diagram of the Ba-Y-Cu-O system, we synthesized a single-phased sample with T
c above 90 K. The crystal structure was determined to be an orthorhombic derivative of the perovskite. It was also found that there exist several other phases competing with the high T
c phase. Among them a tetragonal phase and another orthorhombic phase were obtained in a single-phased state, the former being non-superconducting above 1.3 K, while the latter superconducting below 60 K. The effects of composition and sintering conditions on the physical properties of these phases are briefly reported.
Cryogenic Transmission Electron Microscopy of High Tc Ba-Yb-Cu Perovskite Oxide
Authors: Ishida Yoichi , Takahashi Yutaka , Mori Minoru , Iwatsuki Masashi
Published: November 2005

A high-T
c superconductor Ba-Yb-Cu perovskite oxide was examined by a high resolution cryogenic transmission electron microscope. The result are compared with observations at room temperature. Lattice images of the superconducting layered perovskite were recorded in spite of expected disturbing Meissner effect. Anormalous changes in the diffraction spots and lattice images were recorded in some of the layered crystals. The change may reflect perturbations either in the lattice or local magnetic flux.
Schottky Barrier Height of Al/n-In0.53Ga0.47As and Nb/n-In0.53Ga0.47As Diodes
Authors: Tamura Hirotaka , Yoshida Akira , Muto Shunichi , Hasuo Shinya
Published: November 2005

The barrier heights of Al/n-In0.53Ga0.47As and Nb/n-In0.53Ga0.47As diodes were measured using standard current-voltage and current-temperature techniques. An Al film was evaporated in situ on MBE-grown n-InGaAs. A Nb film was deposited by rf sputtering on an Ar sputter cleaned surface. The barrier height was 0.2 eV for the Al/n-InGaAs diode, and below 0.1 eV for the Nb/n-InGaAs diode.
Electronic Structure of High Tc Superconducting Layered Perovskite La-Cu-O and Y-Ba-Cu-O by LMTO Method
Authors: Fujiwara Takeo , Hatsugai Yasuhiro
Published: November 2005

The electronic energy bands are calculated for the high T
c superconducting materials La2CuO4, YBa2Cu3O8 and YBa2Cu3O6 by the LMTO-ASA method. The Cu:3d (x2-y2, 3z2-r2) bands show several varieties near the Fermi energy.
Oxygen Deficiency and Cu Valence States of Superconducting Y-Ba-Cu Oxide
Authors: Fukushima Noburu , Yoshino Hisashi , Niu Hiromi , Hayashi Masaru , Sasaki Hideyuki , Yamada Yutaka , Murase Satoru
Published: November 2005

The oxygen deficiency, Cu valence states and superconducting properties were analized on Y0.4Ba0.6CuO3-x
. The critical temperature and the normal-state resistivity varied depending on the change of CuIII/CuII ratio and/or the oxygen deficiency caused by the sintering atmospheres.
Superconducting and Transport Properties of B-Y-Cu-O Compounds –Orthorhombic and Tetragonal Phases
Authors: Hatano Takeshi , Matsushita Akiyuki , Nakamura Keikichi , Sakka Yoshio , Matsumoto Takehiko , Ogawa Keiichi
Published: November 2005

The superconducting properties and crystal structures of the Ba-Y-Cu-O compounds have been studied. Annealing and quenching experiments have been carried out to study the phase transformation between the high temperature tetragonal phase (oxygen deficient) and low temperature orthorhombic phase (oxygen rich). The former phase is semiconductor-like down to 4.2 K, whereas the latter is metallic and superconducting with T
c as high as 94 K. The conspicuous difference in the transport and superconducting properties between the two phases has been attributed to the loss or formation of oxygen and Cu atom chain in the crystal structure.
High Tc Superconductivity in Screen Printed Yb-Ba-Cu-O Films
Authors: Koinuma Hideomi , Hashimoto Takuya , Nakamura Takashi , Kishio Kohji , Kitazawa Koichi , Fueki Kazuo
Published: November 2005

Screen printing was proved to be a promising method for the preparation of superconducting films having transition temperatures higher than the boiling point of liquid nitrogen. The film properties were highly sensitive to the substrate material. A Yb-Ba-Cu-O film prepared on yttria stabilized zirconia (YSZ) substrate has T
c onset and zero resistivity temperatures of 99.1 K and 77.2 K, respectively.
Some Problems in the Preparation of Superconducting Oxide Films on Ceramic Substrates
Authors: Koinuma Hideomi , Kawasaki Masashi , Hashimoto Takuya , Nagata Shunroh , Kitazawa Koichi , Fueki Kazuo , Masubuchi Kiyomi , Kudo Masahiro
Published: November 2005

Factors significantry influencing the properties of films prepared from high T
c superconducting perovskite type oxides on ceramic substrates have been investigated. For the realization of superconductivity of films, it was verified that not only the composition and crystal structure of the films but also the interaction with substrate materials must be carefully controlled.
ESR and Magnetic Susceptibility in Y2BaCuO5
Authors: Kojima Kenichi , Ohbayashi Kohji , Udagawa Masayuki , Hihara Tadamiki
Published: November 2005

ESR and magnetic susceptibility measurements were made in insulating Y2BaCuO5. A uniaxial type of the ESR spectrum was observed at room temperature and was found to be due to Cu2+ ions by an intensity measurement. The g values parallel and perpendicular to the symmetry axis are 2.24±0.02 and 2.06±0.02, respectively. Susceptibility measurements showed that the Curie constant is (0.22±0.1) emu·K/mol and the paramagnetic Curie temperature is (-8±1) K. The small value of the Curie constant suggests that the sample contains some oxygen deficiency.
Effects of Magnetic and Non-Magnetic Impurities on Anisotropic Singlet Superconductors
Authors: Maekawa Sadamichi , Isawa Yoshimasa , Ebisawa Hiromichi
Published: November 2005

We examine effects of magnetic and non-magnetic impurities on superconductors with anisotropic Cooper pairs of spin-singlet and calculate the tunneling density of states. When the Cooper pair has no component with s-symmetry, magnetic impurities result in the same pair-breaking effect as non-magnetic ones, which is weaker than the usual time-reversal symmetry breaking. The recently discovered high T
c magnetic superconducting oxides, R-Ba-Cu-O with R being rare-earth ions, are discussed in the light of the present theory.
Superconductivity in YBa2Cu3-yNiyO7-δ
Authors: Maeno Yoshiteru , Nojima Tsutomu , Aoki Yuji , Kato Masatsune , Hoshino Kenichi , Minami Asao , Fujita Toshizo
Published: November 2005

Superconductivity in alloyed compounds YBa2Cu3-y
Ni
y
O7-δ has been studied in order to gain direct insights on the roles different Cu sites play in electrical conduction. Electron probe microanalysis as well as X-ray powder diffraction analysis shows that Ni is actually substituted for Cu in the oxygen-deficient perovskite compound for y at least as much as 0.27. Electrical resistivity measurements revealed that the substituted Ni does not substantially destroy the superconductivity.
Temperature Dependence of Anomalous Magnetism of High-Tc Superconductors –Rare-Earth-Ba-Cu Oxides–
Authors: Minami Hidetoshi , Masumi Taizo , Hikami Shinobu
Published: November 2005

A series of high-T
c superconductors, Eu-, Gd- and Ho-Ba-Cu oxides have been found to indicate the coexistence either of a large parasite magnetization or a magnetically ordered phase together with superconductivity by using a microwave SQUID.
X-Ray Single Crystal Structure Analysis of Tetragonal Ba2YCu3-xO7-y, a High Temperature Form of the Superconductor
Authors: Nakai Izumi , Sueno Shigeho , Okamura Fujio P. , Ono Akira
Published: November 2005

Crystal data: tetragonal, space group P4/mmm, a=3.8640(4), c=11.755(3) Å, final R factor=0.036 for 161 independent observed reflections. Cu1 and two O1 form linear O-Cu-O dumbell (Cu-O1 1.808 Å) with additional square planer O2 group (site occupancy=0.2) around Cu1. Cu2 is in square pyramidal coordination of oxygen composed of square-planer O3 group (Cu-O3 1.944 Å) and an apical O1 (Cu-O1 2.434 Å). The Y and Ba are in ordered arrangement along the c axis. This tetragonal phase is a high temperature form of the orthorhombic phase and the transition is related with ordering of the oxygen vacancy. Presence of strong metal-metal interactions were presumed because there exist Ba-Ba, Ba-Y and Ba-Cu distances significantly shorter than sum of their corresponding metallic radii.
Magnetic Field Effects in the High-Tc Superconductor Y-Ba-Cu-O
Authors: Nakao Masao , Nemoto Masaaki , Yuasa Ryohkan , Mukaida Hiromi , Terakado Singo , Shikichi Kazuaki , Mizukami Atsuo
Published: November 2005

The single-phase compound YBa2Cu3O7 prepared in pure oxygen atmosphere exhibited an extremely high upper critical field H
c2 (0 K) above 110 T (midpoint) as well as high T
c above 92 K (end point). Magnetic field dependence of resistance R has been measured as a function of temperature T. Shoulders appeared in the R-T transition curves of (Y1-x
Ba
x
)CuO3-y
(x=0.6) prepared in air, suggesting the coexistence of two kind of phases, i.e., a high-H
c2 phase and a low-H
c2 phase. H
c2(77 K) defined by a zero-resistance state was at most ∼0.05 T in the low-H
c2 phase.
Characterization of Metamorphic Phases of Ba2YCu3O9-δ
Authors: Nakazawa Yasuhiro , Ishikawa Masayasu , Takabatake Toshiro , Koga Kei-ichi , Terakura Kiyoyuki
Published: November 2005

We have recently found several metamorphic phases of Ba2YCu3O9-δ. In addition to the high T
c orthorhombic phase, two tetragonal and another orthorhombic phases of them were studied with X-ray diffraction, susceptibility and resistivity measurements. We found that the high T
c phase is a weak Pauli paramagnet and one of the tetragonal phases is a magnetic semiconductor with a phase transition around 8 K. The results are briefly discussed in relevance to the superconductivity in this series of oxides.
Oxygen Deficiency in YM2Cu3O7+y (M=Ba, Sr) Family
Authors: Oda Migaku , Murakami Toshiaki , Enomoto Yoichi , Suzuki Minoru
Published: November 2005

YBa2Cu3O7+y
samples, slowly cooled after annealing, are orthorhombic and exhibit a complete transition at 90 K. On the contrary, rapidly quenched samples are tetragonal and their T
c's are 20 K lower than those of the slowly cooled ones. It is found from thermogravimetric analysis that the amount of oxygen deficiency in the tetragonal samples is greater than the orthorhombic ones. This fact indicates that the structural difference is attributed to both the disordering of oxygen vacancies and the difference in oxygen vacancy amount. In addition, YSr2Cu3O7+y
samples are tetragonal and exhibit complete transition at 81 K.
The Meissner Effect of the Small Single Crystals of Ba2YCu2.89O6.80
Authors: Oda Yasukage , Kohara Takao , Nakada Ichiroh , Fujita Hiroshi , Kaneko Tetsuyuki , Toyoda Haruhisa , Sakagami Eiji , Asayama Kunisuke
Published: November 2005

Single crystals of Ba2YCu2.89O6.80 compound responsible for superconductivity were prepared in average size of several hundred microns. The Meissner effect of these single crystals was measured. The crystal structure and the deficiency of oxygen and copper of this specimen have been determined by X-ray diffraction method.
Superconducting and Structural Properties of the New Ba1-xLnxCuO3-y Compound System (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb)
Authors: Ohshima Shigetoshi , Wakiyama Tokuo
Published: November 2005

The Ba1-x
Ln
x
CuO3-y
compounds (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb) with x=0.34 and (Ln=Nd, Sm and Eu) with x=0.2, 0.4 and 0.5 were prepared. A superconducting transition between 75 and 93 K was observed magnetically in the compounds (Ln=Nd, Sm, Eu, Ho and Er) with x=0.34. X-ray studies showed that most compounds with high T
c have the oxygen-defect perovskite structure.
Upper Critical Field Measurements by Pulsed Magnetic Fields in High-Tc Supoerconducting Oxides
Authors: Okuda Kiichi , Noguchi Satoru , Yamagishi Akio , Sugiyama Kiyohiro , Date Muneyuki
Published: November 2005

Upper critical fields of high-T
c superconducting oxides, La1.85Sr0.15CuO4-δ, Y0.4Ba0.6CuO
y
and YBa2Cu3O7-δ, were measured by magnetoresistance method under a pulsed magnetic field up to 60 T in a temperature region 4.2 K to T
c. The H
c2
(0) defined by the midpoint of the resistive transition are estimated to be 40, 90 and 148 tesla, for La1.85Sr0.15CuO4-δ, Y0.4Ba0.6CuO
y
and YBa2Cu3O7-δ, respectively.
Composition Dependence of Superconductivity in Y-Ba-(Ag, Co)-O System
Authors: Saito Yoshitami , Noji Takashi , Endo Akihiko , Higuchi Naoaki , Fujimoto Kenji , Oikawa Tokuju , Hattori Atsuhiko , Furuse Kazuyuki
Published: November 2005

High T
c superconductors, YBa2(Ag
x
Cu1-x
)3O9-y
with composition of 0≦x≦0.6 were prepared by a ceramic technique, and the compositional change of T
c was examined. Samples with nominal compositions of x<0.4, expecially YBa2(Ag0.1Cu0.9)3O9-y
and YBa2(Ag0.2Cu0.8)3O9-y
, show sharp superconducting transitions with widths as narrow as about 1 K or less. The superconductivity is discussed in relation to the results of X-ray diffraction study.
Determination of Valence of Copper and Oxygen Deficiency in Superconducting SrxLa2-xCuO4-y
Authors: Saito Yoshitami , Noji Takashi , Hirokawa Kichinosuke , Endo Akihiko , Matsuzaki Nozomu , Katsumata Masao , Higuchi Naoaki
Published: November 2005

We report the analytical results of Cu valence and the amount of oxygen deficiency in high T
c superconductors, Sr
x
La2-x
CuO4-y
. These results show that for the sample with x=0, the valence state of all Cu ion is proved to be Cu2+. Amount of Cu3+ and oxygen deficiency linearly increase with increasing Sr. According to this, there is no clear correlation between the transition temperature and the oxygen deficiency.
Lateral Solid-Phase Epitaxy of Si Induced by Focused Ion Beams
Authors: Kanayama Toshihiko , Tanoue Hisao , Komuro Masanori
Published: November 2005

Thin 200-nm-thick Si crystals were grown in Si layers amorphized with 800-keV As2+ ions by inducing lateral solid-phase epitaxy at 500°C with a 140-keV Si2+ psuedo-linear ion beam formed by scanning a point-focused beam at 5 kHz. It is shown that reduction of dose rate of the ion beam is crucially important to induce the epitaxy because the amount of damage produced by the ions significantly increases with the dose rate and even amorphization occurs at a higher dose rate.
Composition Dependence of the Physical Properties in the Superconducting Y-Ba-Cu-O System
Authors: Tajima Hiroyuki , Maeda Atsushi , Kobayashi Mototada , Satake Tohru , Shimada Hiromichi , Miyama Susumu , Kuroda Haruo
Published: November 2005

The structural, electronic and magnetic properties were investigated for the high T
c superconductor (Y1-x
Ba
x
)3Cu3O7-y
where x was in the range of 0.0 to 0.9. Superconduction was found for samples with 0.4≤x≤0.8. The transition temperature of the single phase with x=0.7 was 92 K. In contrast with the previously reported (La1-x
Ba
x
)2CuO4-y
system, the replacement of yttrium ions by barium ions was not observed for the Y-Ba-Cu-O system.
Sharp Superconductivity Transition at 94 K in HoBa2Cu3O7-δ and ErBa2Cu3O7-δ
Authors: Takita Kôki , Akinaga Hiroyuki , Katoh Hideo , Ippōshi Takashi , Masuda Kohzoh
Published: November 2005

We report the results of temperature dependences of the resistivity and the magnetic susceptibility in (a) HoBa2Cu3O7-δ and (b) ErBa2Cu3O7-δ whose structure and phase are confirmed by Rietveld analysis of X-ray powder diffraction. (a)- and (b)-compounds show a very sharp superconductivity transition at 94 K with the transition width of 1.0 K and 1.4 K, respectively, strongly suggesting that these samples consist of a single-phase superconductor. According to a simultaneous investigation of the structural properties on the same samples, it is strongly suggested that the orthorhombic phase is the superconducting phase at 94K both in (a)- and (b)-compounds, which is proposed recently as a dominant polymorphs of YBa2Cu3O7-δ.
Raman and Infrared Spectra of a Green Y2BaCuO5-y
Authors: Udagawa Masayuki , Ogita Norio , Fukumoto Akira , Utsunomiya Yoshiharu , Ohbayashi Kohji
Published: November 2005

Raman scattering and infrared absorption spectra of a green Y2BaCuO5-y
were measured at room temperature. Many lattice vibrational modes were observed.
Studies on the Thermal Behavior of Ba2YCu3O7-x by X-Ray Powder Diffraction Method
Authors: Yukino Ken , Sato Tadao , Ooba Shigeki , Ohta Masatsune , Okamura Fujio P. , Ono Akira
Published: November 2005

Thermal behavior of Ba2YCu3O7-x
was investigated mainly by X-ray powder diffraction method between 70 K and 1173 K. Oxygen-rich(x∼0.5) specimen is orthorhombic in symmetry in the temperature range between 70 K and 943 K. It undergoes a phase transition to tetragonal form at 943 K or 783 K in air or N2 gas, respectively. On the other hand, oxygen-poor specimen(x∼1.0) semiconductive down to 4.2 k is tetragonal up to 1173 K in N2 gas. Thermal expansion coefficient of a cell parameter is about 1.1 × 10-5 K-1 and that of c cell parameter is 2.5 × 10,,5 K-1, in air.
Superconducting Behavior of YBa2Cu3O7 under Pressure
Authors: Akahama Yuichi , Endo Shoichi , Noguchi Satoru , Okuda Kiichi
Published: November 2005

Superconducting transition temperature (T
c) of YBa2Cu3O7 indicated a slight decreasing tendency, as a whole, with increasing pressure up to 1.75 GPa. A faint maximum of T
c around 0.5 GPa may be correlated with the observed change in the sign of the temperature dependence of the electrical resistance in the normal state.
Radiative Recombination Mechanism of EL2 Level in GaAs
Authors: Tajima Michio
Published: November 2005

A clear account is given of the recombination mechanism for deep-level luminescence associated with the midgap donor EL2 in GaAs by photoluminescence excitation (PLE) spectroscopy. The deep-level emission band excited in the photon energy range of 0.8-1.5 eV is shown to consist of the 0.63 and 0.68 eV bands. The 0.63(0.68) eV band is explained as the radiative transition between the conduction (valence) band and the empty (occupied) EL2 level, on the basis of the agreement of the spectral distribution of the PLE spectra with the optical cross-sections of the EL2 level. This assignment is strongly confirmed by the occurrence of the photoquenching effect and by the disappearance of the 0.68(0.63) eV band in n(p)-type semiconductive materials.
n-ITO/p-InGaAsP Solar Cell Fabricated on GaAs Substrate
Authors: Narui Hironobu , Matsubara Shuichi , Takahashi N. Shin-ichi , Kurita Shoichi
Published: November 2005

n-ITO/p-InGaAsP solar cells have been fabricated. Lattice-matched LPE growth of InGaAsP layers on GaAs has been carried out before the ITO film is deposited by rf sputtering. The best cell without an antireflection coating exhibits a conversion efficiency of 9.6% under AMI illumination and the corresponding open-circuit voltage, short-circuit current density, and fill factor are 0.6 V, 24.5 mA/cm2, and 0.653, respectively.
GaInAs/InP Hot Electron Transistors Grown by OMVPE
Authors: Ishihara Kanji , Kinoshita Satoru , Furuya Kazuhito , Miyamoto Yasuyuki , Uesaka Katsumi , Miyauchi Motoya
Published: November 2005

GaInAs/InP hot electron transistors were fabricated for the first time by using an organometallic vapor phase epitaxy (OMVPE) method. A base transport efficiency was measured as 0.52 at 77 K for the structure of a 160 nm thick Ga0.47In0.53As base and InP barrier layers. High energy peaks observed in current spectra suggested an appreciable hot electron transport. These show a promising potential of the OMVPE grown GaInAs/InP for its use in ballistic electron devices.
Carrier Transport Mechanisms Based on the Short-Circuit Photocurrent versus Open-Circuit Voltage Characteristics of Spray-Deposited SnO2/SiO2/n-Si Solar Cells
Authors: Nagatomo Takao , Omoto Osamu
Published: November 2005

To analyze the mechanisms of carrier transport in spray-deposited SnO2/SiO2/n-Si solar cells, the dark current-voltage characteristics and the short-circuit photocurrent (J
sc)-open-circuit voltage (V
oc) characteristics were measured by varying the illumination on the solar cell. This investigation of the J
sc-V
oc characteristics provides useful information for understanding the relation between the photovoltaic properties and the carrier transport mechanisms.
Injection-Current-Controlled Bistable Optical Switching in Semiconductor Laser Amplifiers
Authors: Ogasawara Nagaatsu , Ito Ryoichi , Asabayashi Issei , Ohashi Makoto
Published: November 2005

A new bistable optical switch with large optical gain is demonstrated using a semiconductor laser amplifier. The optical output is switched between the two stable states, the “on” and “off” states, by injecting trigger-current pulses of ∼1 mA amplitude and ∼1 ns width superimposed on a DC bias. Output powers of the order of 1 mW can be obtained in the “on” state in response to input powers of several tens of µW.
Observation of Magnetization Structure on Co-Cr Perpendicular Magnetic Recording Media by Bitter and Electron Holography Methods
Authors: Honda Yukio , Futamoto Masaaki , Kawasaki Takeshi , Yoshida Kazuetsu , Koizumi Makoto , Kugiya Fumio , Tonomura Akira
Published: November 2005

The magnetization structure of single-layer Co-Cr media recorded with a ring head at 20 and 100 kFCI is investigated along with the microstructure of Co-Cr film prepared by vacuum deposition. A stronger magnetization as well as a deeper penetration of perpendicular magnetization have been realized with the highly-oriented Co-Cr films consisting of pillar-like c-axis-oriented Co-Cr columns. This magnetic behavior is considered necessary to achieve a high-density and high-output perpendicular magnetic recording when the medium is combined with a ring head.
ESR Microscopic Imaging with Microfabricated Field Gradient Coils
Authors: Ikeya Motoji , Miki Toshikatsu
Published: November 2005

A high microscopic resolution of electron spin resonance (ESR) imaging was obtained by inserting small field gradient coils into a microwave cavity. Anti-Helmholtz coil pairs with diameters between 0.5 mm and 4 mm and spacing distances of 1 mm-3 mm produced a field gradient of 20 T/m (2 kG/cm) at a pin-hole region. The resolution of less than 1 µm can be obtained for the signal of DPPH particles. One dimensional imaging was tried using the colloid signal of NaCl irradiated by X-rays to indicate the possibility of microdosimetry.
Fabrication of GaAs/AlGaAs GRIN-SCH Lasers with Newly Developed Ridge Waveguide
Authors: Yagi Katsumi , Yamauchi Hideki , Yamaguchi Takao , Niina Tatsuhiko
Published: November 2005

In this paper, a new ridge fabrication method is demonstrated. The upside cladding region is composed of two different Al mole fraction AlGaAs layers which have been selectively etched to form a ridge waveguide. GaAs/AlGaAs graded-index waveguide separate-confinement heterostructure (GRIN-SCH) lasers with this newly developed ridge waveguide have shown high external differential quantum efficiencies, with a maximum of 80% for a 4 µm × 250 µm cavity.
High-Frequency Heterodyned Detection of Picosecond Accumulated Photon Echoes
Authors: Saikan Seishiro , Fujiwara Atsushi , Kushida Takashi , Kato Yoshiaki
Published: November 2005

Highly sensitive detection of accumulated photon echoes was achieved by means of a high-frequency heterodyned method using a mode-locked CW dye laser. Experimental results on the modulation frequency dependence of the echo signal strength and also the excitation wavelength dependence of the echo decay curves in Nd:silicate glass are presented.
Temperature Coefficients of Resistivity of Rh-Fe Thin Films for Cryogenic Thermometer Use
Authors: Tamura Osamu , Sakurai Hirohisa
Published: November 2005

The resistivity and its temperature coefficients were measured on Rh-Fe thin films between 4.2 K and room temperature to estimate their thermometric sensitivity. The films were sputter deposited on sapphire substrates from a Rh-Fe(0.5 atm%) target. The temperature coefficients are close to those of high-purity, well-annealed Rh-Fe(0.5 atm%) wires although the resistivity is higher than that of the wires. Rh-Fe thin film resistors have a high potential for cryogenic thermometers because dilute iron in the films is as effective as that in bulk wires to enhance the temperature coefficients.
Surface Structures Observed by High-Resolution UHV Electron Microscopy at Atomic Level
Authors: Takayanagi Kunio , Tanishiro Yasumasa , Kobayashi Kunio , Akiyama Kazuhiro , Yagi Katsumichi
Published: November 2005

The dynamic processes and structure of an Au cluster growing from a few to several tens of atoms have been revealed using a new high-resolution electron microscope designed specially for in situ surface study at atomic level. The in situ microscopy has also clarified details of the reconstructed structure of Au(100)5×1 and (110)2×1 surfaces formed on particles using profile images. In the reflection microscope mode, the 7×7 reconstructed structure of the Si(111) surface has been seen with 2.3 nm superlattice fringes. In situ high-resolution electron microscope observations in transmission and reflection modes are thus demonstrated to be useful for studies of the dynamic behavior of surfaces.
Fine Structure of As-Quenched Omega-Phase of Ti-Mo Alloy Observed by HREM with Image Processing
Authors: Sukedai Eiichi , Hashimoto Hatsujiro , Hida Moritaka
Published: November 2005

The structure of the omega-phase which is formed by the quenching of Ti-14 wt%Mo alloy from 1223 K to 273 K was investigated at the atomic level using a high-resolution electron microscope (HREM). The HREM image were formed by using 15 diffracted waves including diffuse scattering due to the omega-phase. The focus of imaging was adjusted to aberration-free-focus (AFF) condition and the observed images were processed by a computer to reveal the structure of the omega-phase only. It was found that the omega-phase co-exists with an omega-like structure formed by vacancy clusters.
Formation Conditions of SiO2 and FeO Grains
Authors: Kaito Chihiro , Shoji Rihito , Fujita Kazuo
Published: November 2005

The growth conditions of SiO2 and FeO grains have been elucidated by using a molybdenum silicide heater to evaporate SiO and Fe powders separately in a gas mixture of Ar and O2. Crystalline grains of β-cristobalite were produced above 650 Pa of oxygen partial pressure. FeO grains were produced at about 650 Pa of oxygen partial pressure. These grains were produced by the oxidation of SiO and Fe grains in the gas mixture.
Approach to Superlattice of Transition Metal Coordination Compounds by Selective Coordinating Epitaxy
Authors: Takahashi Kazuhiro , Tanino Hiroshi , Yao Takafumi
Published: November 2005

A double heterostructure of transition metal coordination compounds (TMCC), [PtII(en)2][PtIVX2(en)2]Y4(abbreviated as `X'), where en=1,2-diaminoethane, X=Cl, Br, Y=ClO4 or BF4, is grown by selective coordination epitaxy (SCE) for the first time. The fact indicates that superlattice of TMCC can be realized by SCE. A heterostructure including the mixed-crystal `Cl1-x
Br
x
' (Y=ClO4) is also reported. The band structure of the superlattice of TMCC's can be controlled continuously in the same manner as that of GaAs/Al1-x
Ga
x
As/AlAs superlattice and reference is made to the polarized reflectance spectra of the mixed-crystals.
Upper Critical Fields of Ba2YCu3O9-δ
Authors: Takabatake Toshiro , Ishikawa Masayasu , Nakazawa Yasuhiro , Oguro Isamu , Sakakibara Toshiro , Goto Tuneaki
Published: November 2005

The temperature dependence of the upper critical field H
c2 of the high T
c superconductor Ba2YCu3O9-δ was measured resistively between 0 and 40 T on a single phased sample with T
c=92 K. The critical field defined as the midpoint of the transition reaches 34 T at the boiling point of liquid-nitrogen. From the initial slope of the H
c2(T) curve of - 1.27 T/K, the electronic specific heat coefficient was estimated to be 7.5 mJ/mol·K2 using the dirty limit approximation.
Sharp Resonance Characteristics in Triple-Barrier Diodes with a Thin Undoped Spacer Layer
Authors: Nakagawa Tadashi , Fujita Takahiro , Matsumoto Yutaka , Kojima Takeshi , Ohta Kimihiro
Published: November 2005

The effect of an undoped spacer layer up to 300 A thick adjoining a triple-barrier diode is studied. Larger peak-to-valley ratios and smaller full-widths at half maximum (FWHM), compared to conventional triple-barrier diodes, are obtained for the resonant current-peaks in these samples. It is explained that a main cause of the peak broadening is the random distribution of silicon ions in the heavily doped layer adjoining the barrier.
Crystal Structure of the High Tc Superconductor ErBa2Cu3O7-δ
Authors: Ishigaki Tōru , Asano Hajime , Takita Kôki
Published: November 2005

The crystal structure of the high T
c superconductor ErBa2Cu3O7-δ has been determined by X-ray powder diffraction combined with the Rietveld analysis. The compound is isostructural with homologous superconductors YBa2Cu3O7-δ and HoBa2Cu3O7-δ. In the orthorhombic structure (space group Pmmm) with lattice parameters a=3.8781(1) Å, b=3.8128(1) Å and c=11.6644(3) Å, Er and Ba are ordered, O in the z=1/2 plane is completely missing and O on the basal plane is deficient.
STM Images of Graphite Dependent on Size of the Tip
Authors: Horie Chuji , Miyazaki Hiroshi
Published: November 2005

A simple model is presented to investigate the effect of the size of the tip in a scanning tunneling microscope on the image of graphite. In the model, the tip and carbon atoms of the surface of graphite are replaced by circles with areas effective to the local tunneling currents. It is shown that the STM images reflect the hexagonal arrangement of carbons but differ depending on the size of the tip.