Tsutomu Ishimasa
Emeritus Professor, Hokkaido University[Present Position]
Fellow at Toyota Physical and Chemical Research Institute[Research Field]
Metal physics, Crystal physics[Date of Birth]
March 15, 1952

[Sex] Male[Nationality] Japan[EDUCATION]
1971-75 in Materials Science
Department of Materials Physics, School of Engineering Science, Osaka University.
1975-80 in Materials Science
Department of Materials Science, Graduate School of Science, Hiroshima
University.
1981
Doctor of Science, Hiroshima University[Professional Career]
April, 1980 - May, 1984

Research Associate, Department of Physics, College of General Education,
Nagoya University

June, 1984 - March, 1986

Visiting Researcher, Solid State Physics, ETH-Zurich

April, 1986 - Sep., 1986

Research Associate, Department of Physics, College of General Education,
Nagoya University

Oct., 1986 - Sep., 1989

Assistant Professor, Department of Physics, College of General Education,
Nagoya University

Oct., 1989 - Sep., 1993

Associate Professor, Department of Physics, College of General Education,
Nagoya University

Oct., 1993 - March, 2000

Associate Professor, Department of Physical Engineering, School ofEngineering, Nagoya University

April 2000 - March, 2015

Professor, Division of Applied Physics, Graduate School of Engineering,
Hokkaido University

April 2015 - March, 2017

Specially appointed professor, Division of Applied Physics, Graduate Schoolof Engineering, Hokkaido University

April 2017 - present

Fellow, Toyota Physical and Chemical Research Institute[AWARDS]
Latsis Prize of ETH-Zurich, Nov. 1986

Research Overview
Quasicrystals and their physical properties
Tsutomu Ishimasa
1. Introduction
The history of mankind is often classified as Stone age, Bronze age, Iron age, and Silicon age.
The main role here is solid, and in most cases it is crystalline. The quasicrystals studied by thepresent author are new solid states recognized in 1984 and have been expected as new functional
materials due to the specificity of the structure. We have been studying quasicrystals with a primary
focus on the structure and contributing to the establishment of a new concept called quasicrystals.
As is well known, crystals are formed by the periodic arrangement of atoms. This periodicity isreflected in the band structure and is the basis of the properties of each substance. On the other hand,in quasicrystals, atoms are arranged obeying unexpected rules such as "regular but not periodic".
Regularity of the quasicrystal is related to "geometric progression" in the ideal state, while theperiodicity of the crystal is to "arithmetic progression". The common ratio of the geometricprogression is a certain irrational number like golden ratio. This special regularity is called"quasiperiodicity".
"How electrons behave at quasiperiodic potential" is an important issue. From the theoretical
calculations of one- and two-dimensional systems, it is expected that a special state appears, which
is not similar to the extended state in a crystal nor to the localized state in an amorphous. (This iscalled "critical state".) Therefore, electronic properties inherent to quasicrystals are expected, andhave been searched for a long time. However, no clear indication of them was found before theobservation of the quantum criticality in Au-Al-Yb quasicrystal (see Section 3.).
Furthermore, quasicrystals are also different from crystals in terms of rotational symmetry. In
crystals, rotational symmetry is limited to those that are compatible with periodicity. On the other
hand, in the case of quasicrystals, "high symmetry"such as 12-fold symmetry, which is not permitted in
crystals, is possible in the reciprocal space (see Figure1). Such symmetry is thought to reflect on theelectronic structure through the shape of
pseudo-Brillouin zone, which affects physicalproperties and also phase stability.
When trying to conduct experimental research fromthese viewpoints, it is a problem that "Quasiperiodicity close to the ideal can be formed in realmaterial ?". With this problem in mind, we havecarried out the following two themes: "A new seriesof icosahedral quasicrystal" and "A new dodecagonalquasicrystal". Below, the results of research after2000 are summarized.

2. New series of icosahedral quasicrystals in Zn-, Cu and Au-based alloys
In 2000 new stable quasicrystal, Cd-Yb, was reported by the group of Prof. A.P. Tsai (Tohoku
Univ.). Stimulated by this discovery, we explored quasicrystals and reached a new series. They are
Zn-M-Sc alloys with M=Mg, Mn, Fe, Co, Ni, Pd, Ag, Pt and Au. This series includes many stablequasicrystal phases. We also found the first Cu-based quasicrystals in Cu-Al-Sc and Cu-Ga-Mg-Sc
alloys, the latter of which is a stable phase. Furthermore,ternary Au-based quasicrystals were also discovered.
Among others, the structural integrity of Zn-Mg-Sc
quasicrystal (Figure 2) was extremely high, and thediffraction peaks measured using synchrotron radiation had
the same sharpness as the crystal. This fact indicates thatquasiperiodicity is realized with the same degree ofcompleteness as periodicity in a real matter. (It should be
noted that this is true only for some selected quasicrystals.)
The presence of a series of quasicrystals indicates thatthese quasicrystals have "diversity as alloy" capable ofelement substitution. From this diversity, crude conditions necessary for forming this type ofquasicrystals was known. They are conditions for the atomic size relation and the valence-electron
concentration e/a. They correspond to the famous conditions known as Hume-Rothery rules ofcrystalline alloys. The condition for the valence-electron concentration is explained by theformation of a pseudo gap resulting from the interaction between the Fermi-surface and thepseudo-Brillouin zone with the "sphere like shape". In this way, physical property controle byelement substitution, or material design, became possible to a certain extent. The results mentioned
in the next section is this application example.
On the other hand, "approximant crystals" having a composition similar to quasicrystals are often
formed in these alloys; for example, Au 51 Al 35 Yb 14 approximant for Au 51 Al 34 Yb 15 quasicrystal. An
approximant is composed of local structural unit, called cluster, similar to that included in thecorresponding quasicrystal. The approximant can be used as a reference material in structural
studies of quasicrystals and physical propeties.
For details, see the following reference.
・New Group of Icosahedral Quasicrystals, T. Ishimasa, "Quasicrystals, Handbook of Metal
Physics", Chapter 3, pp 49-74, edited by T. Fujiwara and Y. Ishii, Elsevier (Amsterdam), 2008.

3. Valence-fluctuating quasicrystal and its quantum criticality
As described above, in the quasicrystal, a critical electronic state has been expected. On the other
hand, in the alloy containing a rare earth element in the valence fluctuating state, the problem ofitinerant/localized state of the 4f electron has been studied from the viewpoint of magnetism andstrongly correlated electron system. One may think that it is interesting if a quasicrystal thatcombines both properties is formed. The first quasicrystal satisfying this condition is Au 51 Al 34 Yb 15
alloy discovered by our research group. In the preceding study, we have found Yb-containing
quasicrystals in Zn-Mg-Yb and Ag-Ga-(Mg)-Yb alloys. However, in these alloys valency of Yb is+2, and they show no interesting magnetic properties. Intermediate valency +2.6 of Yb in the
Au-Al-Yb quasicrystal was found by fortunate coincidence.
By collaboration with Deguchi/Stao group of Nagoya University, it has been clarified that
Au-Al-Yb quasicrystal exhibits specific temperature dependence of magnetism, electronic specificheat, and electrical resistance at cryogenic temperatures. Figure 3 shows the temperaturedependence of the magnetic susceptibility χ. The magnetic susceptibility χ rapidly increase at the
low-temperature side at T -0.51, and appears to diverge
at T=0 in the case of magnetic field H~0. Actually, as
seen in the inset, χ-1 has a linear relationship with T
0.51, and the straight line passes through the origin.
This is the dependence different from the Curie low
proportional to T -1. In addition, divergence tendency
was also observed in the temperature dependence ofthe electronic specific heat coefficient. Furthermore,
although the divergence of the magnetic susceptibility
is suppressed by the application of the magnetic field,
it does not depend on the pressure (see the inset of
Figure 3). These experimental results show that aunique quantum critical state "insensitive to pressure"occurs in the Au-Al-Yb quasicrystal. As pressure
usually changes the degree of sf hybridization, suchinsensitivity to pressure is not an example in crystal.
On the other hand, in the Au-Al-Yb approximant crystal having a composition similar to that of
the quasicrystal, the susceptibility shows a finite value at the limit of T=0. This indicates occurrenceof "Heavy fermion" similar to that observed in ordinary valence-fluctuating crystals. Recent
research has further revealed that the temperature dependence of the magnetic susceptibility of theapproximant is greatly affected by the application of pressure, and that it also shows quantum
criticality at approximately 2 GP. This clear difference between the approximant and thequasicrystal suggests that the unique quantum criticality is a phenomenon inherent to a quasicrystal.
For details, please refer to the following two papers.
・Icosahedral quasicrystal and 1/1 cubic approximant in Au-Al-Yb alloys, T. Ishimasa, Y.
Tanaka, and S. Kashimoto, Phil. Mag. 91, 4218-4229 (2011).
・Quantum critical state in a magnetic quasicrystal, K. Deguchi, N.K. Sato, T. Hattori, K. Ishida,
H. Takakura and T. Ishimasa, Nature Materials, 11, 1013-1016 (2012).

4. Dodecagonal quasicrystals
In 1985, the authors found the first "dodecagonal quasicrystal" in Ni-Cr alloy particles of about1000 Å in diameter. This is a "two-dimensional quasicrystal" with a 12-fold symmetry axis as wellas quasiperiodicity in the plane perpendicular to the axis. This is the third kind of quasicrystal
following the icosahedral and the decagonal quasicrystals*. However, as of around 1990, thedodecagonal quasicrystals were limited to the fine particles and some other rapidly quenched alloys,
and the research in the metal field came to a dormant state.
* This result was cited as reference 13 in the official document of the Nobel Prize in Chemistry2011 "Scientific background on the Nobel Prize in Chemistry 2011: The Discovery of
Quasicrystals".
On the other hand, recently, dodecagonalquasicrystals have been discovered one after
another in ceramics such as mesoporous silica,
polymers such as micelle-forming dendrimer and
ABC star polymer, and surfaces such as very thinlayer of BaTiO 3 on Pt (111). By these discoveries,
the universality of the dodecagonal order in thematerial world has become clear. Then, we
resumed research on alloys around 2010. The
target is a stable metallic dodecagonal quasicrystal with structural quality comparable to theordinary crystal.
A new alloy was searched experimentally
starting from two kinds of approximant known in
Mn-Cr-Si alloy, which are respectively high- andlow-temperature phases. As a result, a new
dodecagonal quasicrystal was discovered as an alloy containing 1 at.% of Ni (Figure 4). The
conventional dodecagonal quasicrystals in alloys are formed through non-equilibrium treatment
such as quenching, whereas this quasicrystal is formed by aging from β-Mn type crystal. Therefore,
it can be said that this is one step closer to the stable quasicrystal. A high resolution electron
microscope image is presented in Figure 4. Tiling of squares and equilateral tringles (edge length
4.6 Å) is observed, which is the feature of the dodecagonal quasicrystal. The squares and triangles
further form regular dodecagons as indicated in the figure. However, as a result of detailed analysis,
it became clear that quasiperiodicity was kept only within a limited range of about 100 Å indiameter. It is still an unsolved problem to synthesize dodecagonal quasicrystals with high degree ofstructural perfection. This result was published in the following paper.
・Phason space analysis and structure modeling of 100 Å-scale dodecagonal quasicrystal in
Mn-based alloy, T. Ishimasa, S. Iwami, N. Sakaguchi, R. Oota and M. Mihalkovič, Phil. Mag.
95 3745-3767 (2015).

5. Other important result: Dynamical flexibility in Zn 6 Sc approximant
In the series of quasicrystals and theirapproximants mentioned in Section 2, westudied both static and dynamical structures,
as well as physical properties such as
magnetism. Among them, the mostimportant result is dynamical flexibility
related to the central structure of the cluster.
In the case of Zn 6 Sc approximant, this is
the rotation like motion of the Zn tetrahedron in THz order (see Figure 5). This movement is similar
to the rattling, except that the four Zn atoms move together holding the shape of the tetrahedron. At
low temperature below approximately 150K, the movement stops and an ordered structure isformed. This new phenomenon named dynamical flexibility was clarified from the results of X-ray
structure analysis at low temperature as well as neutron quasi-elastic scattering experiment at higher
temperature. It is surprising that such a dynamical phenomenon occurs inside a hard and brittle
intermetallic compound. For details, please refer to the following two papers.
・Low-temperature phase of the Zn-Sc approximant, T. Ishimasa, Y. Kasano, A. Tachibana, S.
Kashimoto and K. Osaka, Phil. Mag., 87, Nos. 18-21, 2887-2897 (2007).
・Ordering and dynamics of the central tetrahedron in the 1/1 Zn 6 Sc periodic approximant toquasicrystal, H. Euchner, T. Yamada, H. Schober, S. Rols, M. Mihalkovič, R. Tamura, T.
Ishimasa and M. de Boissieu, J. Phys. Cond. Mat., 24, 415403-1-9 (2012).

PUBLICATIONS
Tsutomu Ishimasa
Original papers(1) Electrical resistivity of Gd(Al1-xCux)2, J. Sakurai, T. Ishimasa and Y. Komura, J. Phys.
Soc. Jpn., 43, 1589-1593, (1977).
(2) Direct observation of the intersection of sequence faults in the Fe-Crσ-phase, T. Ishimasa,
Y. Kitano and Y. Komura, Jpn. J. Appl. Phys., 19, L483-L486, (1980).
(3) Electron microscope observation of lattice defects in the Fe-Crσ-phase, T. Ishimasa, Y.
Kitano and Y. Komura, J. Solid State Chem., 36, 74-80, (1981).
(4) Faulted structure in the Fe-Crσ-phase, T. Ishimasa, Y. Kitano and Y. Komura, phys. stat.
sol. (a), 66, 703-715, (1981).
(5) Crystal structure and morphology of fine particles of vanadium silicides, T. Ishimasa andY. Fukano, Jpn. J. Appl. Phys., 22, 6-11, (1983).
(6) Planar defect in A15 structure observed in Cr-Si fine particles, T. Ishimasa and Y. Fukano,Jpn. J. Appl. Phys., 22, 1092-1097, (1983).
(7) Nonperiodic electron microscopic structure images of Al-Mn, H.-U. Nissen, T. Ishimasa,
R. Schlogl, P. Reiman and H. Guntherodt, Helvetica Phys. Acta, 58, 819-822, (1985).
(8) Crystal structure and morphology of Ni-Cr fine particles, T. Ishimasa and Y. Fukano,
Surface Sci., 156, 241-248, (1985).
(9) New ordered state between crystalline and amorphous in Ni-Cr particles, T. Ishimasa,
H.-U. Nissen and Y. Fukano, Phys. Rev. Lett., 55, 511-513, (1985).
(10) Superconducting transition temperature of fine A15 V-Si alloy particles, S. Matsuo, T.
Ishimasa and Y. Fukano, J. Phys. Soc. Jpn., 55, 2790-2797, (1986).
(11) Electron microscopy and image contrast calculation of Al-Mn quasicrystal, T. Ishimasa
and H.-U. Nissen, Physica Scripta, T13, 291-296, (1986).
(12) Magnetic susceptibility and electrical resistivity of RGa6 (R=rare earth metals), Y.
Tagawa, J. Sakurai, Y. Komura and T. Ishimasa, J. Less-Comm. Met., 119, 269-275,(1986).
(13) V51 Knight shift in fine V3Si particles, K. Koyama, S. Matsuo, Y. Suzuki, T. Ishimasa
and Y. Fukano, Jpn. J. Appl. Phys., 26, 2138-2139, (1987).
(14) Orientation relation between icosahedral and crystalline phases in Al-Mn alloys, C. Beeli,
T. Ishimasa and H.-U. Nissen, Phil. Mag. B, 57, 599-608, (1988).
(15) Quasicrystal structure in Al-Cu-Fe annealed alloy, T. Ishimasa, Y. Fukano and M.
Tsuchimori, Phil. Mag. Lett., 58, 157-165, (1988).

(16) High-temperature magnetic properties of a stable Al65Cu20Fe15 icosahedral phase, S.
Matsuo, T. Ishimasa, H. Nakano and Y. Fukano, J. Phys. F, 18, 175-L180, (1988).
(17) Dislocations, domains and quenched phonon and phason strains in Al-Mn quasicrystals
observed by electron microscopy, D.N. Wang, T. Ishimasa, H.-U. Niseen, S. Hovmoller
and J. Rhyner, Phil. Mag. A, 58, 737-752, (1988).
(18) Electron microscopy of crystalloid structure in Ni-Cr small particles, T. Ishimasa, H.-U.
Nissen and Y. Fukano, Phil. Mag. A, 58, 835-863, (1988).
(19) Magnetic properties and the electronic structure of a stable Al-Cu-Fe icosahedral phase, S.
Matsuo, H. Nakano, T. Ishimasa and Y. Fukano, J. Phys.: Condens.Matter, 1, 6893-6899,(1989).
(20) Millimeter-size single quasicrystals in Al-Cu-Fe alloy, T. Ishimasa and M. Mori, Phil.
Mag. Lett., 62, 357-364, (1990).
(21) Photoemission study of an Al-Cu-Fe icosahedral phase, M. Mori, S. Matsuo, T. Ishimasa,
T. Matsuura, K. Kamiya, H. Inokuchi and T. Matsukawa, J. Phys.: Condens. Matter, 3,
767-771, (1991).
(22) X-ray diffuse scattering of an Al-Cu-Fe single quasicrystal, M. Mori, T. Ishimasa and
Y .Kashiwase, Phil. Mag. Lett., 64, 49-57, (1991).
(23) Resonant photoemission study of the Al-Cu-Fe icosahedral phase, M. Mori, K. Kamiya, S.
Matsuo, T. Ishimasa, H. Nakano, H. Fujimoto and H. Inokuchi, J. Phys.: Condens. Matter,
4, L157-L162, (1992).
(24) Crystal structures of small Al-rich Fe alloy particles formed by a gas-evaporation
technique, M. Tsuchimori, T. Ishimasa and Y. Fukano, Phil. Mag. B, 66, 89-108, (1992) .
(25) New superlattice ordering in Al-Pd-Mn and Al-Pd-Mn-Si icosahedral quasicrystals, T.
Ishimasa and M. Mori, Phil. Mag. B, 66, 513-532, (1992).
(26) Magnetic and electrical properties of the single-grained Al-Cu-Fe icosahedral phase, S.
Matsuo, T. Ishimasa, M. Mori and H. Nakano, J. Phys.: Condens. Matter, 4, 10053-10060,(1992).
(27) Magnetic properties of an icosahedral phase of Ga-Mg-Zn alloy, K. Saito, S. Matsuo and T.
Ishimasa, J. Phys. Soc. Jpn., 62, 604-611, (1993).
(28) Transmission electron microscope analysis og grain boundaries, twinns, and planar
defects in Cr2B- and Fe2B-type borides, K. Kotani, T. Ishimasa and T. Oki, J. JapanInst.
Metals, 57, 125-134 (1993) in Japanese.
(29) Crystallographic characterization of a single quasicrystal of Al-Cu-Fe, X.B. Kan, J.
Robertson, S.C. Moss, J. Kulik, T. Ishimasa, M. Mori, A. Quivy, D. Gratias, V. Elser and P.

Zschack, J. Non-Crys. Solids, 153&154, 33-39, (1993).
(30) Use of periodic approximants in the structure refinement of icosahedral Al-Cu-Fe, E.
Cockayne, R. Phillips, X.B. Kan, S.C. Moss, J. Robertson, T.Ishimasa and M.Mori, J.
Non-Crys. Solids, 153&154, 140-144, (1993).
(31) Temperature-independent contribution in weak localization theory and Boltzman
conductivity in a single-grained icosahedral Al-Cu-Fe quasicrystal, S. Matsuo, H. Nakano,
K. Saito, M. Mori and T. Ishimasa, Solid State Comm., 86, 707-710, (1993).
(32) Anisotropic magnetic property of single-grained Al68Pd23Mn9 icosahedral quasicrystals,
S. Matsuo, H. Nakano, T. Ishimasa and M. Mori, J. Phys. Soc. Jpn, 62, 4044-4052, (1993).
(33) Magnetic and electrical properties of a single-grained Al70Pd21Mn9 icosahedral
quasicrystal, K. Saito, S. Matsuo, H. Nakano, T. Ishimasa and M. Mori, J. Phys. Soc. Jpn,
63, 1940-1947, (1994).
(34) Temperature-independent contribution in weak localization theory with spin scattering ina single-grained Al-Pd-Mn icosahedral quasicrystal, S. Matsuo, H. Nakano, T. Ishimasa
and M. Mori, Solid State Comm., 92, 811-814, (1994).
(35) Superlattice ordering in Al-Pd-Mn low-temperature icosahedral phase, T. Ishimasa, Phil.
Mag. Lett., 71, 65-73, (1995).
(36) Magnetic susceptibility change in the Al-Pd-Mn icosahedral quasicrystals obeying timedependence of phason relaxation, S. Matsuo, T. Ishimasa and H. Nakano, Solid State
Comm., 102, 575-578, (1997).
(37) Magnetic properties of F and P type icosahedral quasicrystals of Al-Pd-Mn, A. Kobayashi,
S. Matsuo, T. Ishimasa and H. Nakano, J.Phys.:Condensed Matter, 9, 3205-3217, (1997).
(38) Crystal structure of a cubic Al70Pd23Mn6Si; a 2/1 rational approximant of an icosahedralphase, K. Sugiyama, N. Kaji, K. Hiraga and T. Ishimasa, Z. Krisllogr., 213, 90-95, (1998).
(39) Crystal structure of a cubic Al67Pd11Mn14Si7; a new 1/1 rational approximant for the
Al-Pd-Mn icosahedral phase, K. Sugiyama, N. Kaji, K. Hiraga and T. Ishimasa, Z.
Krisllogr., 213, 168-173, (1998).
(40) Reversible transformation between an icosahedral AlPdMn phase and a modulated
structure of cubic symmetry, M. de Boissieu, M. Boudard, T. Ishimasa, E. Elkaim, J.P.
Lauriat, A. Letoublon,M. Audier, M. Duneau and A. Davroski, Phil. Mag. A., 78, 305-326,(1998).
(41) Formation of F- and P-type icosahedral quasicristals in the Zn-Mg-Ho alloy system, T.
Shimizu and T. Ishimasa, Jpn. J. Appl. Phys., 37,5691-5696, (1998).
(42) Magnetic and electrical properties of a stable Zn-Mg-Ho icosahedral quasicrystal, S.

Kashimoto, S. Matsuo, H. Makano, T. Shimizu and T. Ishimasa, Solid State Comm., 109,
63-67, (1999).
(43) Stability of the F2-AlPdMn phase, A. Letoublon, T. Ishimasa, M. de Boissieu, M. Boudard,
B. Hennion, M. Mori, Phil. Mag. Lett.,

80, 205-213, (2000).

(44) Microdomain structure in the disordered Zn-Mg-Ho icosahedral phase, T. Ishimasa and T.
Shimizu, Jpn. J. Appl. Phys., 39,1235-1240, (2000).
(45) Formation conditions of two quasiperiodic modifications of Al-Pd-Mn icosahedral phasestudied by annealing method, I. Hirai, T. Ishimasa, A. Letoublon, M. Boudard and M. de
Boissieu, Mater. Science Eng., 294-296, 33-36, (2000).
(46) Phase transition and diffuse scattering studies in the AlCuFe ternary system, M. Boudard,
A. Letoublon, M. de Boissieu, T. Ishimasa. M. Mori, E. Elkaim and J.P. Lauriat, Mater.
Science Eng., 294-296, 217-220, (2000).
(47) Long-range and short-range F-type ordering in Zn-Mg-Ho icosahedral phase, T. Ishimasa
and T. Shimizu, Mater. Science Eng., 294-296, 232-236, (2000).
(48) Development of 3D visualization system for the study of physical properties ofquasicrystals, H. Nakano, Y. Sato, S. Matsuo and T. Ishimasa, Mater. Science Eng.,
294-296, 542-547, (2000).
(49) Dependence of electrical resistivity and magnetoresistance on long range (F-type)ordering in Zn-Mg-Ho icosahedral quasicrystals, S. Kashimoto, H. Nakano, Y. Arichika, T.
Ishimasa and S. Matsuo, Mater. Science Eng., 294-296, 588-591, (2000).
(50) Antiferomagnetic orderes in Ising model simulations in an icosahedral Zn-Mg-Ho
Structure, S. Matsuo, T. Ishimasa and H. Nakano, Mater. Science Eng., 294-296, 633-637,(2000).
(51) Icosahedral quasicrystal in annealed Zn-Mg-Sc alloys, Y. Kaneko, Y. Arichika and T.
Ishimasa, Phil. Mag. Lett., 81,777-787 (2001).
(52) Quasiperiodic long-range ferrimagnetic order in Ising model simulation in an icosahedral
quasicrystal model structure, S. Matsuo, T. Ishimasa and H. Nakano, J. Mag. Mag. Mater,
246, 223-232, (2002).
(53) Cu-based icosahedral quasicrystal formed in Cu-Ga-Mg-Sc alloy, Y. Kaneko, R. Maezawa,H. Kaneko and T. Ishimasa, Phil. Mag Lett., 82, 483-493 (2002).
(54) Millimeter-sized single icosahedral quasicrystal of Zn-Mg-Sc alloy, Y. Kaneko and T.
Ishimasa, Jpn. J. Appl. Phys., 41, L1112-1115 (2002).
(55) A Zn-based icosahedral quasicrystal classified into the same structure type as Cd-based
icosahedral quasicrystals? T. Ishimasa, Y. Kaneko and H. Kaneko, J. Alloys. Comp., 342,

13-17 (2002).
(56) Ten-fold-like magnetic anisotropy in electrical conductivity of Al-Pd-Mn icosahedral
quasicrystal, T. Mizutani, H. Nakano, S. Kashimoto, Y. Takatani, M. Mori, T. Ishimasa
and S. Matsuo, J. Alloys. Comp., 342, 360-364 (2002).
(57) Magnetic property of a Zn-Mg-Sc icosahedral quasicrystal, S. Kashimoto, H. Nakano, Y.
Kaneko, T. Ishimasa and S. Matsuo, J. Alloys. Comp., 342, 384-388 (2002).
(58) Magnetic property of F2M-type Al-Pd-Mn quasicrystals, S. Motomura, T. Ishimasa, I.
Hirai, S. Kashimoto, H. Nakano and S. Matsuo, J. Alloys. Comp., 342, 393-396 (2002).
(59) A new series of icosahedral quasicrystals in Zn-M-Sc (M=Ag, Au, Pd, Pt) alloys, S.
Kashimoto, R. Maezawa, Y. Kasano, T. Mitani and T. Ishimasa, Jpn. J. Appl. Phys., 42,
L1268-1271 (2003).
(60) New group of stable icosahedral quasicrystals - structural properties and formation
conditions, T. Ishimasa, H. Kaneko and Y. Kaneko, J. Non-Crys. Solids, 334-335, 1-7(2004).
(61) Formation condition of stable Cu-Ga-Mg-Sc icosahedral quasicrystal, Y. Kaneko, R.
Maezawa and T. Ishimasa, J. Non-Crys. Solids, 334-335, 8-11 (2004).
(62) Structure analysis of Zn-Mg-Ho icosahedral quasicrystal by modified Rietveld method
using ellipsoid and sphere windows, T. Ishimasa, K. Oyamada, Y. Arichika, E. Nishibori,
M. Takata, M. Sakata and K. Kato J. Non-Crys. Solids, 334-335, 167-172 (2004).
(63) Magnetic and electrical properties of a new type Zn-Mg-Sc icosahedral quasicrystal, S.
Motomura, Y. Kaneko, S. Kashimoto, H. Nakano, T. Ishimasa and S. Matsuo, J. Non-Crys.
Solids, 334-335, 393-397 (2004).
(64) Magnetic and electrical properties of Cu-Ga-Mg-Sc icosahedral quasicrystals, H. Yamada,S. Motomura, R. Maezawa, H. Nakano, T. Ishimasa and S. Matsuo, J. Non-Crys. Solids,
334-335, 398-402 (2004).
(65) Long range antiferromagnetic order in Ising model simulations in two-dimensional
Penrose lattice, S. Matsuo, S. Fujiwara, H. Nakano and T. Ishimasa, J. Non-Crys. Solids,
334-335, 421-426 (2004).
(66) Icosahedral quasicrystals in Zn-T-Sc (T=Mn, Fe, Co, Ni) alloys, R. Maezawa, S.
Kashimoto and T. Ishimasa, Phil. Mag. Lett., 84, 215-223 (2004).
(67) Magnetic property of stable icosahedral quasicrystal in Zn-Fe-Sc, S. Kashimoto, S.
Motomura, R. Maezawa, S. Matsuo and T. Ishimasa, Jpn. J. Appl. Phys., 43, L526-L529(2004).
(68) Electrical Properties of a Stable Icosahedral Quasicrystal Zn-Fe-Sc, S. Motomura, S.

Kashimoto, R. Maezawa, T. Ishimasa and S. Matsuo, J. Phys. Soc. Jpn., 73, 3111-3114(2004).
(69) Ising spin orderes conforming to the local matching rule and simulated spin structures inPenrose lattice, S. Matsuo, T. Ishimasa and H. Nakano, J. Phys. Soc. Jpn., 74, No. 3,1036-1043 (2005).
(70) Diffuse scattering and phason fluctuations in the Zn-Mg-Sc icosahedral quasicrystal and
its Zn-Sc periodic approximant, M. de Boissieu, S. Francoual, Y. Kaneko and T. Ishimasa,
Phys. Rev. Lett., 95, 105503-1-4 (2005).
(71) A metastable icosahedral quasicrystal in the Zn-Mg-Yb alloy system, T. Mitani and T.
Ishimasa, Phil. Mag., 86, Nos. 3-5, 361-366 (2006).
(72) Systematic study of magnetic properties in Zn-based Tsai-type icosahedral quasicrystals
and their approximant, S. Kashimoto, S. Motomura, S. Francoual, S. Matsuo and T.
Ishimasa, Phil. Mag., 86, Nos. 3-5, 725-732 (2006).
(73) Simulation study on antiferromagnetic order of Ising spins in a Zn-Mg-Ho model structure,
S. Matsuo, A. Aimurula, T. Ishimasa, S. Motomura and H. Nakano, Phil. Mag., 86, Nos.
3-5, 741-745 (2006).
(74) Ising spin orders and magnetic interactions analyzed in phason space in a 2-dimensional
Penrose lattice, S. Matsuo, S. Motomura and T. Ishimasa, Phil. Mag., 87, No.1, 51-61(2007).
(75) New icosahedral quasicrystals in Cu-based ternary alloys, T. Honma and T. Ishimasa, Phil.
Mag., 87, Nos. 18-21, 2721-2726 (2007).
(76) Low-temperature phase of the Zn-Sc approximant, T. Ishimasa, Y. Kasano, A. Tachibana,S. Kashimoto and K. Osaka, Phil. Mag., 87, Nos. 18-21, 2887-2897 (2007).
(77) Formation condition and magnetic properties of p-type icosahedral quasicrystals in
Zn-Fe-Sc-L (L = Ho, Er, Tm) alloys, S. Kashimoto, C. Masuda, S. Motomura, S. Matsuo
and T. Ishimasa, Phil. Mag., 87, Nos. 18-21, 2929-2937 (2007).
(78) Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1
approximant, M. de Boissieu, S. Francoual, M. Mihalkovi, K. Shibata, A.Q.R. Baron, Y.
Sidis, T. Ishimasa et al., Nature Materials 6, 977 - 984 (2007) .
(79) Neutron scattering study on spin correlations and fluctuations in the transition-metal-based magnetic quasicrystals Zn-Fe-Sc, T.J. Sato, S. Kashimoto, C. Masuda, T. Onimaru,
I. Nakanowatari, K. Iida, R. Morinaga and T. Ishimasa, Physical Review, B77, 014437:1-7(2008).
(80) Growth of Facetted Microvoids in Zn-Fe-Sc Quasicrystals, T. Ishimasa and J. Matsunagi,

Phil. Mag., 88, 1985-1993 (2008).
(81) Atomic dynamics of the i-ScZnMg and its 1/1 approximant phase: experiment andsimulation, M. Mihalkovic, S. Francoual, K. Shibata, M. de Boissieu, A.Q.R. Baron, Y.
Sidis, T. Ishimasa, et al. Phil. Mag., 88, 2311-2318 (2008).
(82) Magnetic behavior of Fe and Tm in Zn-Fe-Sc-Tm icosahedral quasicrystals, S. Kashimoto,
C. Masuda and T. Ishimasa, Z. Kristallogr., 224, 59-63 (2009).
(83) Crystal structure of 1/0-2/1-1/0 Cu-Al-Sc approximant, T. Ishimasa, A.Hirao, T. Honma
and M. Mihalkovic, Phil. Mag. 91,2594-2602 (2011).
(84) Approximant of dodecagonal quasicrystal formed in Mn-Si-V alloy, H. Iga, M.
Mihalkovic and T.Ishimasa, Phil. Mag. 91, 2624-2633 (2011).
(85) Icosahedral quasicrystal and 1/1 cubic approximant in Au-Al-Yb alloys, T. Ishimasa, Y.
Tanaka, and S. Kashimoto, Phil. Mag. 91, 4218-4229 (2011).
(86) Magnetic properties of σ - and hexagonal-Mn76Si18Cr6 approximant phases of adodecagonal quasicrystal, S. Kashimoto, A. Kocjan, Z. Jagliˇci´c, S. Jazbec, H. Iga, T.
Ishimasa, and J. Dolinsek, Phys. Rev. B84, 224201:1-11 (2011).
(87) Dodecagonal quasicrystals still in progress, T. Ishimasa, Israel J. Chem., 51, 1216-1225(2011).
(88) Ordering and dynamics of the central tetrahedron in the 1/1 Zn6Sc periodic approximant
to quasicrystal, H. Euchner, T. Yamada, H. Schober, S. Rols, M. Mihalkovic, R. Tamura, T.
Ishimasa and M. de Boissieu, J. Phys. Cond. Mat., 24, 415403-1-9 (2012).
(89) Quantum critical state in a magnetic quasicrystal, K. Deguchi, N.K. Sato, T. Hattori, K.
Ishida, H. Takakura and T. Ishimasa, Nature Materials, 11, 1013-1016 (2012).
(90) Tetrahedron dynamics in the icosahedral quasicrystals i-ZnMgSc and i-ZnAgSc and the
cubic 1/1-approximant Zn6Sc, H. Euchner, T. Yamada, S. Rols, T. Ishimasa, Y. Kaneko, J.
Ollivier, H. Schober, M. Mihalkovic and M. de Boissieu, J. Phys. Cond. Mat., 25,
115405-1-10 (2013).
(91) Lattice dynamics in the icosahedral quasicrystals i-AnMgSc and i-ZnAgSc and the cubic
1/1-approximant Zn6Sc, H. Euchner, T. Yamada, S. Rols, T. Ishimasa, J. Ollivier,H.
Schober, M. Mihalkovic and M. de Boissieu, J. Phys. Cond. Mat., 26, 055402-1-7 (2014).
(92) Valence change driven by constituent element substitution in the mixed-valence
quasicrystal and approximant Au-Al-Yb, S. Matsukawa, K. Tanaka, M. Nakayama, K.
Deguchi, K. Imura, H. Takakura, S. Kashimoto, T. Ishimasa and N.K. Sato, J. Phys. Soc.
Jpn,

83, 034705-1-5 (2014).

(93) Transport properties of the Au-Al-Yb quasicrystal and approximant under hydrostaticpressure, S. Matsukawa, K. Tanaka, M. Nakayama, S. Kunikata, K. Deguchi, K. Imura, T.
Ishimasa and N.K. Sato, Acta Physica Polonica A, 126, 527-530 (2014).
(94) Tsai-type quasicrystal and its approximant in Au-Al-Tm alloys, K. Tanaka, Y. Tanaka, T.
Ishimasa, M. Nakayama, S. Matsukawa, K. Deguchi and N.K. Sato, Acta Physica Polonica
A, 126, 603-607 (2014).
(95) Localized electron magnetism in the icosahedral Au-Al-Tm quasicrystal and crystalline
approximant, M. Nakayama, K. Tanaka, S. Matsukawa, K. Deguchi, K. Imura, T. Ishimasa
and N.K. Sato, J. Phys. Soc. Jpn, 84, 024721-1-6 (2015).
(96) Crystal structure of superconducting 1/1 cubic Au-Ge-Yb approximant with Tsai-typecluster, K. Deguchi, M. Nakayama, S. Matsukawa, K. Imura, K. Tanaka, T. Ishimasa and
N.K. Sato, J. Phys. Soc. Jpn, 84, 015002-1-2 (2015).
(97) Superconductivity of Au-Ge-Yb approximants with Tsai-type clusters, K. Deguchi, M.
Nakayama, S. Matsukawa, K. Imura, K. Tanaka, T. Ishimasa and N.K. Sato, J. Phys. Soc.
Jpn, 84, 023705-1-4 (2015).
(98) Thermal expansion of a Au - Al - Yb intermediate valence quasicrystal, T. Watanuki, S.
Kashimoto, T. Ishimasa, et al., Solid State Com., 211, 19-22 (2015).
(99) Dodecagonal quasicrystal in Mn-based quaternary alloys containing Cr, Ni and Si, S.
Iwami and T. Ishimasa, Phil. Mag. Lett., 95, 229-236 (2015).
(100) Phason space analysis and structure modeling of 100 Å-scale dodecagonal quasicrystal in
Mn-based alloy, T. Ishimasa, S. Iwami, N. Sakaguchi, R. Oota and M. Mihalkovič, Phil.
Mag. 95 3745-3767 (2015).
(101) Pressure-driven quantum criticality and T/H scaling in the icosahedral Au-Al-Yb
approximant, S. Matsukawa, K. Deguchi, K. Imura, T. Ishimasa and N.K. Sato, J. Phys.
Soc. Jpn, 85, 063706-1-4 (2016).
(102) Direct observation of heterogeneous valence state in Yb-based quasicrystalline
approximants, M. Matsunami, M. Oura, K. Tamasaku, T. Ishikawa, S. Ideta, K. Tanaka, T.
Takeuchi, T. Yamada, A.P. Tsai, K. Imura, K. Deguchi, N.K. Sato and T. Ishimasa,
Physical Review B, 96, 241102(R)-1-4 (2017).
(103) Discovery of superconductivity in quasicrystals, K. Kamiya, T. Takeuchi, N. Kabeya, N.
Wada, T. Ishimasa, A. Ochiai, K. Deguchi, K. Imura and N.K. Sato, Nature Comm., 9,154-1-8 (2018).
(104) Interpretation of some Yb-based valence-fluctuating crystals as approximants to adodecagonal quasicrystal, T. Ishimasa, M. Mihalokovic, K. Deguchi, H.K. Sato and M. de
Boissieu, Phil. Mag., 98, 2018-2034 (2018).

Proceedings(1) TEM observation and dynamical calculation of image contrast in Al-Mn quasicrystal, T.
Ishimasa and H.-U. Nissen, Proc. XIth Int. Cong. on Electron Microscopy, Kyoto 1986,
p.1533-1534(2) The crystalloid structure in Ni-Cr small particles, T. Ishimasa, Y. Fukano and H.-U.
Nissen, Proc. I.L.L./CODEST workshop on Quasicrystalline Materials, Grenoble 1988,
p.168-177.
(3) Phonons, phasons and dislocations in Al-Mn quasicrystals studied by electron microscopy,
D.N. Wang, T. Ishimasa, H.-U. Niseen and S. Hovmoller, Materials Science Forum, 22-24,
381-396, (1987).
(4) Structure instability of Al-Cu-Fe icosahedral phase, T. Ishimasa, Proc. China-Japanseminars on Quasicrystals, Tokyo 1989, Beijing 1990, p.64-71.
(5) X-ray study of an Al-Cu-Fe single quasicrystal, M. Mori, T. Ishimasa and Y. Kashiwase,
Proc. China-Japan seminars on Quasicrystals, Tokyo 1989, Beijing 1990, p.88-95.
(6) Qualitative characterization of phason strain in Al-Cu-Ru quasicrystals, Y. Kitano, T.
Watanabe and T. Ishimasa, Proc. XIII Int. Cong. on Electron Microscopy, Paris 1994,
p.675-676.
(7) X-ray study of Al-Pd-Mn icosahedral phase, M. Mori and T. Ishimasa, Proc. 5th Int. Conf.
on Quasicrystals, Avignon 1995, p.144-147.
(8) Weak localization and electron-electron interaction effects in Al-Pd-Mn, icosahedralphase, S. Matsuo, H. Nakano and T. Ishimasa, Proc. 5th Int. Conf. on Quasicrystals,
Avignon 1995, p.488-492.
(9) Structural properties and formation conditions of Al-Pd-Mn low-temperature, icosahedralphase, T. Ishimasa, Proc. 5th Int. Conf. on Quasicrystals, Avignon 1995, p.648-651.
(10) Powder X-ray diffraction study of Zn-Mg-Ho icosahedral phase, T. Ohno and T. Ishimasa,
Proc. 6th Int. Conf. on Quasicrystals, Tokyo 1997, p.39-42.
(11) Structure of a 2/1 cubic approximant in the Al-Pd-Mn-Si system, K. Sugiyama, N. Kaji, K.
Yubuta, K. Hiraga and T. Ishimasa, Proc. 6th Int. Conf. on Quasicrystals, Tokyo 1997,
p.199-206.
(12) Phason driven phase transition in the icosahedral phase of AlPdMn, M. de Boissieu, M.
Boudard, T. Ishimasa, E. Elkaim, L.P. Lauriat, A. Letoublon, M. Audier and A. Davroski,
Proc. 6th Int. Conf. on Quasicrystals, Tokyo 1997, p.347-354.
(13) Diffuse scattering of Al-Pd-Mn and Al-Cu-Fe icosahedral phase, M. Mori, T. Ogawa, T.

Ishimasa, M. Tanaka and S. Sasaki, Proc. 6th Int. Conf. on Quasicrystals, Tokyo 1997,
p.387-390.
(14) Anomalously slow change in magnetic susceptibility in Al70Pd21.5Mn8.5icosahedral
quasicrystals obeying time dependence of phason relaxation, S. Matsuo, T. Ishimasa andH. Nakano, Proc. 6th Int. Conf. on Quasicrystals, Tokyo 1997, p.467-470.
(15) X-ray diffuse scattering in icosahedral AlPdMn phase and relations with a phase transition,
A. Letoublon, M. de Boissieu, M. Boudard, M. Audier, J.P. Simon, T. Ishimasa and J.F.
Berar, Proc. Int. Conf. on Aperioic Crystals, Alpe d'Huez 1997, p.439-443.
(16) Diffuse scattering and Huang scattering in Al-based icosahedral quasicrystals, M. Mori, T.
Ishimasa, M. Tanaka and S. Sasaki, Advanced Materials and Processing - PRICM 3,
Honolulu 1998, p.1455-1460.
(17) Ising model simulation of magnetic structures in a Zn-Mg-Ho structure model, S. Matsuo,
T. Ishimasa and H. Nakano, Mat. Res. Soc. Symp. Proc. Vol. 553,1999, p.427-432.
(18) Structure properties of Zn-based icosahedral quasicrystals: Superlattice ordering andatomic clusters, T. Ishimasa, Advanced Materials and Processing - PRICM 4, Honolulu
2001,71-74.
(19) Formation of icosahedral quasicrystal in Zn-Mg-Sc alloy, Y. Kaneko and T. Ishimasa,
Advanced Materials and Processing - PRICM 4, Honolulu 2001, 2523-2526.
(20) Search and synthesis of new family of quasicrystals, T. Ishimasa, S. Kashimoto and R.
Maezawa, Mat. Res. Soc. Symp. Proc. Vol. 805, 2004, 3-14.
(21) Hume-Rothery rule as a formation condition of new icosahedral quasicrystals, T. Ishimasa,
TMS symposium proceedings "The science of complex alloy phases", San Francisco, 2005,
231-250.
(22) Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic
properties, S. Kashimoto and T. Ishimasa, Topology in ordered phases, Proceedings of the
1st International Symposium on TOP2005,Sapporo (World Scientific, Singapole,2006), p.
145-150.
(23) Low-temperature phase transition in Zn-Sc crystalline approximant, A. Tachibana, Y.
Kasano and T. Ishimasa, Proc. 16th International Microscopy Congress, Sapporo 2006,
p.1783.
(24) Icosahedral facceted microvoids in Zn-Fe-Sc quasicrystal, J. Matsunagi and T. Ishimasa,
Proc. 16th International Microscopy Congress, Sapporo 2006, p.1784.
(25) Atomic Dynamics in Complex Metallic Alloys, H. Euchner, S. Pailhes, T. Yamada, R.
Tamura, T. Ishimasa, S.Rols, H. Schober, M. Mihalkovic, H-R. Trebin, D. Schpf, S.

Bhler-Paschen, A. Haghighirad, F. Ritter, W. Assmus, Y. Grin, L. Nguyen and M. de
Boissie, MRS Proceedings 1517 (2013); doi:10.1557/opl.2013.38.
(26) Dynamical flexibility in the periodic Zn6Sc 1/1-aapproximant, H. Euchner, T. Yamada, H.
Schober, S. Rols, M. Mihalkovic, R. Tamura, T. Ishimasa, and M. de Boissieu, Aperiodic
Crystals, eds. S. Schmid, R. L. Withers, R. Lifshitz, Springer, 2013, pp. 253-260. ISBN
978-94-007-6431-6.
(27) Magnetic Properties of the Au-Al-Yb Approximant under Hydrostatic Pressure, S.
Matsukawa, K. Deguchi, K. Imura, T. ishimasa and N.K. Sato, J. Physics Conf. Series,
809, 012013-1-5 (2017).
(28) Aging effects of dodecagonal quasicrystal formed in Mn-Cr-Ni-Si alloys, K. Toyonaga
and T. Ishimasa, J. Physics Conf. Series, 809, 012015-1-4 (2017).
(29) Quantum critical behavior in magnetic quasicrystals and approximant crystals, N. K. Sato,
S.Matsukawa, K. Nobe, K. Imura, K. Deguchi and T. Ishimasa, J. Physics Conf. Series,
868, 012005-1-7 (2017).

Book(1) New Group of Icosahedral Quasicrystals, T. Ishimasa, "Quasicrystals, Handbook of Metal
Physics", Chapter 3, pp 49-74, edited by T. Fujiwara and Y. Ishii, Elsevier (Amsterdam),
2008.

Others(1) Preface: The Eleventh International Conference on Quasicrystals, T.Ishimasa and Y.Ishii,
Phil. Mag., 91, 2419-2420, (2011).
(2) Scientifc commentaries: Mysteries of icosahedral quasicrystals: how are the atoms
arranged ?, T. Ishimasa, IUCrJ, 3, 230-231 (2016).