Doctor of Science, The University of Electro-Communications, Mar. 2012

熱電効果

超伝導

第一原理計算

Nanotechnology/Materials, Applied materials, 熱電効果

Natural sciences, Magnetism, superconductivity, and strongly correlated systems, 超伝導

Informatics, Computational science

Oct. 2025 - Present
The University of Electro-Communications, School of Informatics and Engineering Division of General Education, 准教授, Japan

Jan. 2025 - Sep. 2025
Shimane University, 総合理工学部, 准教授

Mar. 2019 - Dec. 2024
Shimane University, Interdisciplinary Faculty of Science and Engineering, 助教

Aug. 2018 - Mar. 2019
大阪大学国際共創大学院学位プログラム推進機構, 特任助教

Apr. 2013 - Jul. 2018
Osaka University, Institute for Academic Initiatives , 特任助教

Pressure-enhanced superconductivity and pressure-induced uniaxial negative thermal expansion in CuAl2 -type NiZr2
Ryunosuke Shimada; Cuiying Pei; Yuto Watanabe; Kota Muroi; Hidetomo Usui; Aichi Yamashita; Yanpeng Qi; Yoshikazu Mizuguchi
Physical Review Materials, 28 Aug. 2026
Scientific journal

Rb(Cd,Zn)4As3 as a new n-type Zintl phase thermoelectric compound
Keigo Ono; Yosuke Goto; Hidetomo Usui; Masayuki Murata; Satoshi Tsutsui; Kazuhiko Kuroki; Yoichi Kamihara; Chul-Ho Lee
Acta Materialia, Apr. 2026, Peer-reviwed
Scientific journal

Axis-Dependent Conduction Polarity: Design Principles and High-Throughput Discovery of Transverse Thermoelectrics
Zan Yang; Xinyi He; Hidetomo Usui; Toshio Kamiya; Takayoshi Katase
Journal of the American Chemical Society, American Chemical Society (ACS), 148, 6, 6704-6715, 04 Feb. 2026, Peer-reviwed
Scientific journal, English

Theoretical study on the possibility of high Tc s± -wave superconductivity in heavily hole-doped infinite layer nickelates
Hirofumi Sakakibara; Ryota Mizuno; Masayuki Ochi; Hidetomo Usui; Kazuhiko Kuroki
Physical Review B, 20 Jun. 2025, Peer-reviwed
Scientific journal

Goniopolar materials for transverse thermoelectric device
Yosuke Goto; Hidetomo Usui; Masayuki Murata; Chul-Ho Lee
JSAP Review, 2025, 250409, Mar. 2025, Peer-reviwed, Invited
Scientific journal, English

Magnetotransport properties and Shubnikov–de Haas oscillations in a type-II nodal-line semimetal candidate n -type Mg3Bi2 single crystal
Yosuke Goto; Masayuki Murata; Hidetomo Usui; Keigo Ono; Joseph P. Heremans; Taichi Terashima; Chul-Ho Lee
Physical Review B, 26 Feb. 2025, Peer-reviwed
Scientific journal

Theoretical study of the crystal structure of the bilayer nickel oxychloride Sr3Ni2O5Cl2 and analysis of possible unconventional superconductivity
Masayuki Ochi; Hirofumi Sakakibara; Hidetomo Usui; Kazuhiko Kuroki
Physical Review B, 18 Feb. 2025, Peer-reviwed
Scientific journal

Pressure-induced superconductivity and robust Tc against external pressure in (Ge,Sn,Pb)Te
Ryo Matsumoto; Kazuki Yamane; Yoshikazu Mizuguchi; Rikuya Ishikawa; Kyohei Takae; Rei Kurita; Hidetomo Usui; Masahiro Ohkuma; Kensei Terashima; Yoshihiko Takano
Journal of Alloys and Compounds, 983, 05 May 2024, Peer-reviwed
Scientific journal

Large nonlinear optical magnetoelectric response in a noncentrosymmetric magnetic Weyl semimetal
Kentaro Shoriki; Keigo Moriishi; Yoshihiro Okamura; Kohei Yokoi; Hidetomo Usui; Hiroshi Murakawa; Hideaki Sakai; Noriaki Hanasaki; Yoshinori Tokura; Youtarou Takahashi
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, 121, 12, 14 Mar. 2024, Peer-reviwed, Weyl semimetals resulting from either inversion ( P ) or time-reversal ( T ) symmetry breaking have been revealed to show the record-breaking large optical response due to intense Berry curvature of Weyl-node pairs. Different classes of Weyl semimetals with both P and T symmetry breaking potentially exhibit optical magnetoelectric (ME) responses, which are essentially distinct from the previously observed optical responses in conventional Weyl semimetals, leading to the versatile functions such as directional dependence for light propagation and gyrotropic effects. However, such optical ME phenomena of (semi)metallic systems have remained elusive so far. Here, we show the large nonlinear optical ME response in noncentrosymmetric magnetic Weyl semimetal PrAlGe, in which the polar structural asymmetry and ferromagnetic ordering break P and T symmetry. We observe the giant second harmonic generation (SHG) arising from the P symmetry breaking in the paramagnetic phase, being comparable to the largest SHG response reported in Weyl semimetal TaAs. In the ferromagnetically ordered phase, it is found that interference between this nonmagnetic SHG and the magnetically induced SHG emerging due to both P and T symmetry breaking results in the magnetic field switching of SHG intensity. Furthermore, such an interference effect critically depends on the light-propagating direction. The corresponding magnetically induced nonlinear susceptibility is significantly larger than the prototypical ME material, manifesting the existence of the strong nonlinear dynamical ME coupling. The present findings establish the unique optical functionality of P - and T -symmetry broken ME topological semimetals.
Scientific journal

Pressure‐Induced Volumetric Negative Thermal Expansion in CoZr₂ Superconductor
Yuto Watanabe; Hiroto Arima; Saori Kawaguchi‐Imada; Hirokazu Kadobayashi; Kenta Oka; Hidetomo Usui; Ryo Matsumoto; Yoshihiko Takano; Takeshi Kawahata; Chizuru Kawashima; Hiroki Takahashi; Aichi Yamashita; Yoshikazu Mizuguchi
Advanced Electronic Materials, Wiley, 14 Mar. 2024, Peer-reviwed, Abstract

The study investigates the thermal expansion and superconducting properties of a CuAl₂‐type (tetragonal) superconductor CoZr₂ under high pressures. High‐pressure synchrotron X‐ray diffraction is performed in a pressure range of 2.9 GPa < P < 10.4 GPa, and it is discovered that CoZr₂ exhibits volumetric negative thermal expansion (NTE) under high pressures. Although uniaxial positive thermal expansion (PTE) along the a‐axis is observed under ambient pressure, it is suppressed by pressure, whereas a large uniaxial NTE along the c‐axis is maintained under the pressure regime. Because of the combination of the suppressed uniaxial PTE along the a‐axis and uniaxial NTE along the c‐axis, volumetric NTE is achieved under high pressure in CoZr₂. The volumetric NTE mechanism is based on the flexible crystal structure caused by the soft Co–Co bond, as observed in the isostructural compound FeZr₂, which exhibits a uniaxial NTE along the c‐axis. High‐pressure electrical resistance measurements of CoZr₂ are performed and confirm superconductivity at 0.03 GPa < P < 41.9 GPa. Because of the coexistence of the two phenomena, volumetric NTE and superconductivity, in CoZr₂ under high pressure, coexistence can be achieved under ambient pressure by tuning the chemical composition after the present observation.
Scientific journal

Low-Temperature Chiral Crystal Structure and Superconductivity in (Pt0.2Ir0.8)3Zr5
Yuto Watanabe; Hiroto Arima; Aichi Yamashita; Akira Miura; Chikako Moriyoshi; Yosuke Goto; Chul Ho Lee; Ryuji Higashinaka; Hidetomo Usui; Shogo Kawaguchi; Kazuhisa Hoshi; Yoshikazu Mizuguchi
Journal of the American Chemical Society, 146, 1, 773-781, 10 Jan. 2024, Peer-reviwed
Scientific journal

Thermoelectric Properties of Zintl Arsenide EuCuAs
Naoto Nakamura; Yosuke Goto; Yuki Nakahira; Akira Miura; Chikako Moriyoshi; Chul-Ho Lee; Hidetomo Usui; Yoshikazu Mizuguchi
Journal of Electronic Materials, Springer Science and Business Media {LLC}, 52, 5, 3121-3131, May 2023, Peer-reviwed
Scientific journal, English

Synthesis and Characterization of a Trigonal Layered Compound AgInS₂
Takahiro Sawahara; Ryo Matsumoto; Yuki Nakahira; Hidetomo Usui; Noriyuki Kataoka; Ryusei Saitou; Takanori Wakita; Takayoshi Yokoya; Aichi Yamashita; Yosuke Goto; Yoshihiko Takano; Akira Miura; Yoshikazu Mizuguchi
ACS Omega, American Chemical Society ({ACS}), 8, 12, 11288-11292, 28 Mar. 2023, Peer-reviwed
Scientific journal, English

Glassy atomic vibrations and blurry electronic structures created by local structural disorders in high-entropy metal telluride superconductors
Yoshikazu Mizuguchi; Hidetomo Usui; Rei Kurita; Kyohei Takae; Md Riad Kasem; Ryo Matsumoto; Kazuki Yamane; Yoshihiko Takano; Yuki Nakahira; Aichi Yamashita; Yosuke Goto; Akira Miura; Chikako Moriyoshi
Materials Today Physics, Elsevier BV, 32, 101019-101019, Mar. 2023
Scientific journal

Sign change in c-axis thermal expansion constant and lattice collapse by Ni substitution in transition-metal zirconide superconductor Co1−xNixZr2
Yuto Watanabe; Hiroto Arima; Hidetomo Usui; Yoshikazu Mizuguchi
Scientific Reports, Springer Science and Business Media {LLC}, 13, 1, 18 Jan. 2023, AbstractRecently, c-axis negative thermal expansion (NTE) was observed in a CoZr2 superconductor and related transition-metal zirconides. Here, we investigated the structural, electronic, and superconducting properties of Co1−xNixZr2 to achieve systematic control of c-axis NTE and switching from NTE to positive thermal expansion (PTE) by Ni substitution. At x ≤ 0.3, c-axis NTE was observed, and the thermal expansion constant αc approached zero with increasing x. At x = 0.4–0.6, c-axis thermal expansion close to zero thermal expansion (ZTE) was observed, and PTE appeared for x ≥ 0.7. On the superconducting properties, we observed bulk superconductivity for x ≤ 0.6, and bulk nature of superconductivity is suppressed by Ni heavy doping (x ≥ 0.7). For x ≤ 0.6, the evolution of the electronic density of states well explains the change in the superconducting transition temperature (Tc), which suggests conventional phonon-mediated superconductivity in the system. By analyzing the c/a ratio, we observed a possible collapsed transition in the tetragonal lattice at around x = 0.6–0.8. The lattice collapse would be the cause of the suppression of superconductivity in Ni-rich Co1−xNixZr2 and the switching from NTE to PTE.
Scientific journal, English

Superconductivity in In-doped AgSnBiTe3 with possible band inversion
Tsubasa Mitobe; Kazuhisa Hoshi; Md. Riad Kasem; Ryosuke Kiyama; Hidetomo Usui; Aichi Yamashita; Ryuji Higashinaka; Tatsuma D. Matsuda; Yuji Aoki; Takayoshi Katase; Yosuke Goto; Yoshikazu Mizuguchi
Scientific Reports, Springer Science and Business Media LLC, 11, 1, Dec. 2021, Abstract

We investigated the chemical pressure effects on structural and electronic properties of SnTe-based material using partial substitution of Sn by Ag_0.5Bi_0.5, which results in lattice shrinkage. For Sn_1−2x(AgBi)_xTe, single-phase polycrystalline samples were obtained with a wide range of x. On the basis of band calculations, we confirmed that the Sn_1−2x(AgBi)_xTe system is basically possessing band inversion and topologically preserved electronic states. To explore new superconducting phases related to the topological electronic states, we investigated the In-doping effects on structural and superconducting properties for x = 0.33 (AgSnBiTe₃). For (AgSnBi)_(1−y)/3In_yTe, single-phase polycrystalline samples were obtained for y = 0–0.5 by high-pressure synthesis. Superconductivity was observed for y = 0.2–0.5. For y = 0.4, the transition temperature estimated from zero-resistivity state was 2.4 K, and the specific heat investigation confirmed the emergence of bulk superconductivity. Because the presence of band inversion was theoretically predicted, and the parameters obtained from specific heat analyses were comparable to In-doped SnTe, we expect that the (AgSnBi)_(1−y)/3In_yTe and other (Ag, In, Sn, Bi)Te phases are candidate systems for studying topological superconductivity.
Scientific journal

Possible pairing mechanism switching driven by structural symmetry breaking in BiS2-based layered superconductors
Aichi Yamashita; Hidetomo Usui; Kazuhisa Hoshi; Yosuke Goto; Kazuhiko Kuroki; Yoshikazu Mizuguchi
Scientific Reports, Springer Science and Business Media LLC, 11, 1, Dec. 2021, Investigation of isotope effects on superconducting transition temperature (T_c) is one of the useful methods to examine whether electron–phonon interaction is essential for pairing mechanisms. The layered BiCh₂-based (Ch: S, Se) superconductor family is a candidate for unconventional superconductors, because unconventional isotope effects have previously been observed in La(O,F)BiSSe and Bi₄O₄S₃. In this study, we investigated the isotope effects of ³²S and ³⁴S in the high-pressure phase of (Sr,La)FBiS₂, which has a monoclinic crystal structure and a higher T_c of ~ 10 K under high pressures, and observed conventional-type isotope shifts in T_c. The conventional-type isotope effects in the monoclinic phase of (Sr,La)FBiS₂ are different from the unconventional isotope effects observed in La(O,F)BiSSe and Bi₄O₄S₃, which have a tetragonal structure. The obtained results suggest that the pairing mechanisms of BiCh₂-based superconductors could be switched by a structural-symmetry change in the superconducting layers induced by pressure effects.
Scientific journal

Bipolar doping and thermoelectric properties of Zintl arsenide Eu5In2As6
Naoki Tomitaka; Yosuke Goto; Kota Morino; Kazuhisa Hoshi; Yuki Nakahira; Hiroaki Ito; Akira Miura; Hidetomo Usui; Yoshikazu Mizuguchi
JOURNAL OF MATERIALS CHEMISTRY A, 9, 46, 26362-26370, Nov. 2021
Scientific journal, English

A comparative study of thermoelectric Cu2TrTi3S8 (Tr = Co and Sc) thiospinels: Enhanced Seebeck coefficient via electronic structure modification
Katsuaki Hashikuni; Koichiro Suekuni; Hidetomo Usui; Raju Chetty; Michihiro Ohta; Toshiro Takabatake; Michitaka Ohtaki
JOURNAL OF ALLOYS AND COMPOUNDS, 871, Aug. 2021
Scientific journal, English

Thermoelectric Properties of the As/P-Based Zintl Compounds EuIn2As2–xPx (x = 0–2) and SrSn2As2
Keisuke Shinozaki; Yosuke Goto; Kazuhisa Hoshi; Ryosuke Kiyama; Naoto Nakamura; Akira Miura; Chikako Moriyoshi; Yoshihiro Kuroiwa; Hidetomo Usui; Yoshikazu Mizuguchi
ACS Applied Energy Materials, American Chemical Society (ACS), 4, 5, 5155-5164, 24 May 2021
Scientific journal

The crystal structure and electrical/thermal transport properties of Li1-xSn2+xP2 and its performance as a Li-ion battery anode material
Yosuke Goto; Shota Nakanishi; Yusuke Nakai; Takeshi Mito; Akira Miura; Chikako Moriyoshi; Yoshihiro Kuroiwa; Hidetomo Usui; Tatsuma D. Matsuda; Yuji Aoki; Yoshifumi Nakacho; Yuto Yamada; Kiyoshi Kanamura; Yoshikazu Mizuguchi
JOURNAL OF MATERIALS CHEMISTRY A, 9, 11, 7034-7041, Mar. 2021
Scientific journal, English

Insulating-Degenerated-Insulating transition observed in electrical properties of mixed anion layered compounds, LaCu_1-δS_0.5Se_0.5O (δ=0-0.02)
Kamihara Yoichi; Azuma Nobuhiko; Sakagami Ryosuke; Usui Hidetomo
JSAP Annual Meetings Extended Abstracts, The Japan Society of Applied Physics, 2021.1, 2941-2941, 26 Feb. 2021
Japanese

複合アニオン層状化合物LaCu[1-δ]S[0.5]Se[0.5]O (δ~0.01)多結晶縮退半導体の光学バンドギャップ内構造—In-gap-states of a Mixed Anion Layered Compound, Polycrystalline LaCu[1-δ]S[0.5]Se[0.5]O (δ~0.01) as a Degenerate Semiconductor
東 伸彦; 伊藤 大平; 澤田 拓希; 坂上 良介; 臼井 秀知; 的場 正憲; 神原 陽一
材料の科学と工学 : 日本材料科学会誌, 東京 : 日本材料科学会 ; 2002-, 58, 2, 64-68, 2021, Peer-reviwed
Scientific journal, Japanese

First Principles Study on the Thermoelectric Performance of CaAl2Si2-type Zintl Phase Compounds
Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 89, 12, Dec. 2020
Scientific journal, English

Thermoelectric Properties of La 1-xSr xZnAsO
Y. Kimura; H. Kunioka; K. Kihou; H. Nishiate; H. Usui; Y. Tokunaga; T. Iida; K. Kuroki; C. H. Lee
Journal of Electronic Materials, Springer, 49, 11, 6715-6720, 01 Nov. 2020
Scientific journal, English

Model Construction and a Possibility of Cupratelike Pairing in a New d(9) Nickelate Superconductor (Nd,Sr)NiO2
Hirofumi Sakakibara; Hidetomo Usui; Katsuhiro Suzuki; Takao Kotani; Hideo Aoki; Kazuhiko Kuroki
PHYSICAL REVIEW LETTERS, 125, 7, Aug. 2020, Peer-reviwed
Scientific journal, English

Thermoelectric Properties of (Ba,K)Zn2As2 Crystallized in the ThCr2 Si-2-type Structure
Haruno Kunioka; Kunihiro Kihou; Daichi Kato; Hidetomo Usui; Tsutomu Iida; Hirotaka Nishiate; Kazuhiko Kuroki; Atsushi Yamamoto; Chul-Ho Lee
INORGANIC CHEMISTRY, 59, 9, 5828-5834, May 2020
Scientific journal, English

Enargite Cu3PS4: A Cu-S-Based Thermoelectric Material with a Wurtzite-Derivative Structure
Takuya Tanimoto; Koichiro Suekuni; Taiki Tanishita; Hidetomo Usui; Terumasa Tadano; Taiga Kamei; Hikaru Saito; Hirotaka Nishiate; Chul Ho Lee; Kazuhiko Kuroki; Michitaka Ohtaki
ADVANCED FUNCTIONAL MATERIALS, 30, 22, May 2020
Scientific journal, English

First-principles Study of LaOPbBiS3 and Its Analogous Compounds as Thermoelectric Materials
Keiya Kurematsu; Masayuki Ochi; Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 89, 2, 024702, Feb. 2020, Peer-reviwed
Scientific journal, English

Hidden robust presence of a hole Fermi surface in a heavily electron-doped iron-based superconductor LaFe2As2
Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW RESEARCH, 1, 3, Oct. 2019
Scientific journal, English

Pressure-induced superconductivity in the layered pnictogen diselenide NdO0.8F0.2Sb1-xBixSe2 (x=0.3 and 0.7)
Ryo Matsumoto; Yosuke Goto; Sayaka Yamamoto; Kenta Sudo; Hidetomo Usui; Akira Miura; Chikako Moriyoshi; Yoshihiro Kuroiwa; Shintaro Adachi; Tetsuo Irifune; Hiroyuki Takeya; Hiromi Tanaka; Kazuhiko Kuroki; Yoshikazu Mizuguchi; Yoshihiko Takano
PHYSICAL REVIEW B, 100, 9, 094528, Sep. 2019, Peer-reviwed
Scientific journal, English

Electronic Structure of Sr1-yCayFe2(As1-xPx)(2) (x=0.25, y=0.08) Revealed by Angle-Resolved Photoemission Spectroscopy
Tom Adachi; Shinichiro Ideta; Zi How Tin; Hidetomo Usui; Kiyohisa Tanaka; Shigeki Miyasaka; Setsuko Tajima
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 88, 8, 084701-084701, Aug. 2019, Peer-reviwed
Scientific journal, English

Large Enhancement of Thermoelectric Efficiency Due to a Pressure-Induced Lifshitz Transition in SnSe
T. Nishimura; H. Sakai; H. Mori; K. Akiba; H. Usui; M. Ochi; K. Kuroki; A. Miyake; M. Tokunaga; Y. Uwatoko; K. Katayama; H. Murakawa; N. Hanasaki
Physical Review Letters, American Physical Society, 122, 22, 226601-226601, 07 Jun. 2019
Scientific journal

Electronic structure and thermoelectric properties of Sn1.2-xNbxTi0.8S3 with a quasi-one-dimensional structure
Koichiro Suekuni; Hidetomo Usui; Siying Qiao; Katsuaki Hashikuni; Tatsuya Hirano; Hirotaka Nishiate; Chul-Ho Lee; Kazuhiko Kuroki; Kosuke Watanabe; Michitaka Ohtaki
JOURNAL OF APPLIED PHYSICS, 125, 17, 175111-175111, May 2019
Scientific journal, English

Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO2
Hidetomo Usui; Masayuki Ochi; Sota Kitamura; Takashi Oka; Daisuke Ogura; Helge Rosner; Maurits W. Haverkort; Veronika Sunko; Philip D. C. King; Andrew P. Mackenzie; Kazuhiko Kuroki
PHYSICAL REVIEW MATERIALS, 3, 4, 045002-045002, Apr. 2019, Peer-reviwed
Scientific journal, English

Theoretical Aspects of the Study on the Thermoelectric Properties of Pnictogen-Dichalcogenide Layered Compounds
Masayuki Ochi; Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 88, 4, 041010-041010, Apr. 2019, Peer-reviwed, Invited
Scientific journal, English

Electronic Structure and Superconducting Gap Structure in BiS2-based Layered Superconductors
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Takuya Nomoto; Kazumasa Hattori; Hiroaki Ikeda
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 88, 4, 041008, 1-13-041008, Apr. 2019
Scientific journal, English

Hidden robust presence of a hole Fermi surface in a heavily electron doped iron based superconductor LaFe $ _2 $ As $ _2$
Usui, Hidetomo; Kuroki, Kazuhiko
arXiv preprint arXiv:1905.05488, 2019
Scientific journal

Thermoelectric Properties and Electronic Structures of CuTi2S4 Thiospinel and Its Derivatives: Structural Design for Spinel-Related Thermoelectric Materials
Katsuaki Hashikuni; Koichiro Suekuni; Hidetomo Usui; Raju Chetty; Michihiro Ohta; Kazuhiko Kuroki; Toshiro Takabatake; Kosuke Watanabe; Michitaka Ohtaki
INORGANIC CHEMISTRY, 58, 2, 1425-1432, Jan. 2019, Peer-reviwed
Scientific journal, English

Thermoelectric properties of (Ba,K)Cd$_2$As$_2$ crystallized in the CaAl$_2$Si$_2$-type structure
H. Kunioka; H. Usui; K. Kuroki
Dalton Transactions, 47, 45, 16205-16210, Dec. 2018, Peer-reviwed
Scientific journal, English

Thermoelectric performance of materials with CuCh(4) (Ch = S, Se) tetrahedra: Similarities and differences among their low-dimensional electronic structure from first principles
Masayuki Ochi; Hitoshi Mori; Daichi Kato; Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW MATERIALS, 2, 8, 085401-085401, Aug. 2018, Peer-reviwed
Scientific journal, English

Evidence for s-wave pairing with atomic scale disorder in the van der Waals superconductor NaSn 2 As 2
Ishihara, K.; Takenaka, T.; Miao, Y.; Tanaka, O.; Mizukami, Y.; Usui, H.; Kuroki, K.; Konczykowski, M.; Goto, Y.; Mizuguchi, Y.
Physical Review B, 98, 2, 020503-020503, 13 Jul. 2018, Peer-reviwed
Scientific journal

Acknowledgement to Reviewers of Condensed Matter in 2017
Rajdep Adhikari; Konstantin Arutyunov; Konstantin Arutyunov; Veer P. S. Awana; Masashi Ban; Bernardo Barbiellini; Timothy M. Benseman; Igor Boettcher; Bogdan Bulka; Annette Bussmann-Holder; Sergio Caprara; Pietro Carretta; Gabriel Caruntu; Shailesh Chandrasekharan; Anderson Silva Chaves; Mucio Amado Continentino; Zbigniew Czechowski; Evandro Vidor Lins De Mello; Kaveh Delfanazari; James H. Edgar; Chris M. Fancher; Carlo Ferdeghini; Nathanacl A. Fortune; Stellato Francesco; Marcel Franz; Sergey Ganichev; Yosuke Goto; Mihale Grbic; Gerardo Gutierrez-Heredia; Silvia Heredia; Silvia Haindl; Takayuki Hasegawa; Friedrich W. Hehl; Markus Holzmann; Alice Hospodkova; Michale Ibison; Masakazu Ichikawa; Steven Johnston; Beata Kalska-Szostko; Jian Kang; Vassilis Kapsalis; Maurice Kibler; Serghei Klimin; Michale Rudolf Koblischka; Gad Koren; Dimitrios Koumoulis; Georgios Koutroulakis; Anna Krzton-Maziopa; Kliment Kugel; Dushyant Kumar; A. L. Kuzemsky; Changgu Lee; Feng-li Lin; Stefano Lupi; Antoine Maignan; Gabriel Merino; Guoxing Miao; Milorad Milosevic; Yoshikazu Mizuguchi; Shunsuke Murai; Karol Nass; Ethan Neil; Irina Novikova; Murray K. Olsen; Toshinori Ozaki; Juan Jose Palacios; Andrei Patrascu; F. M. D. Pellegrino; Mario Pinheiro; Nicola Poccia; Miroslav Pozek; Andrzej Ptok; Shriram Ramanathan; Michale Reshchikov; Christian Santschi; Moritz Sokolowski; Junwoo Song; Can-Li Song; Michale Stone; Boris Svistunov; Orest G. Symko; Lukasz Tomkow; Gerardo F. Torres Del Castillo; Michale Tringides; Soichiro Tsujino; Philip Turner; Gotz S. Uhrig; Hidetomo Usui; Antonio Valletta; Cesar E. P. Villegas; Paul B. Welander; Youichi Yamakawa; Fan Yang; Mohammad Zarenia; Hua-Jin Zhai; You Zhou
CONDENSED MATTER, 3, 1, Mar. 2018
English

Retreat from Stress: Rattling in a Planar Coordination
Koichiro Suekuni; Chul Ho Lee; Hiromi I. Tanaka; Eiji Nishibori; Atsushi Nakamura; Hidetaka Kasai; Hitoshi Mori; Hidetomo Usui; Masayuki Ochi; Takumi Hasegawa; Mitsutaka Nakamura; Seiko Ohira-Kawamura; Tatsuya Kikuchi; Koji Kaneko; Hirotaka Nishiate; Katsuaki Hashikuni; Yasufumi Kosaka; Kazuhiko Kuroki; Toshiro Takabatake
ADVANCED MATERIALS, 30, 13, Mar. 2018, Peer-reviwed
Scientific journal, English

Retreat from Stress: Rattling in a Planar Coordination
Suekuni, Koichiro; Lee, Chul Ho; Tanaka; Hiromi I; Nishibori, Eiji; Nakamura, Atsushi; Kasai, Hidetaka; Mori, Hitoshi; Usui, Hidetomo; Ochi, Masayuki; Hasegawa, Takumi; Nakamura, Mitsutaka; Ohira-Kawamura, Seiko; Kikuchi, Tatsuya; Kaneko, Koji; Nishiate, Hirotaka; Hashikuni, Katsuaki; Kosaka, Yasufumi; Kuroki, Kazuhiko; Takabatake, Toshiro
Advanced materials (Deerfield Beach, Fla.), WILEY-V C H VERLAG GMBH, 30, 13, 1706230-1706230, Feb. 2018, Thermoelectric devices convert heat flow to charge flow, providing electricity. Materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. Thermal conductivity in caged compounds is known to be suppressed by a large vibration of guest atoms, so-called rattling, which effectively scatters phonons. Here, the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)(Sb,As)Sare studied. The results reveal that the Cu atoms in a planar coordination are rattling. In contrast to caged compounds, chemical pressure enlarges the amplitude of the rattling vibration in the tetrahedrites so that the rattling atom is squeezed out of the planar coordination. Furthermore, the rattling vibration shakes neighbors through lone pairs of the metalloids, Sb and As, which is responsible for the low thermal conductivity of tetrahedrites. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.
Scientific journal, English

Hidden Kagome-lattice-like electronic structures in a delafossite compound PtCoO₂
Usui Hidetomo; Ochi Masayuki; Kitamura Sota; Oka Takashi; Ogura Daisuke; Rosner Helge; Haverkort Maurits W.; Sunko Veronika; King Philip; Mackenzie Andrew P.; Kuroki Kazuhiko
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 73.2, 1632-1632, 2018
Japanese

Thermoelectric properties of (Ba, K) Cd 2 As 2 crystallized in the CaAl 2 Si 2-type structure
Kunioka, H.; Kihou, K.; Nishiate, H.; Yamamoto, A.; Usui, H.; Kuroki, K.; Lee, CH
Dalton Transactions, Royal Society of Chemistry, 47, 45, 16205-16210, 2018
Scientific journal

Spin Hall effect in 2D metallic delafossite PtCoO $ _2 $ and vicinity topology
Kitamura, Sota; Usui, Hidetomo; Slager, Robert-Jan; Bouhon, Adrien; Sunko; Veronika; Rosner; Helge; King; Philip DC; Orenstein, Joseph; Moessner, Roderich; Mackenzie, Andrew
arXiv preprint arXiv:1811.03105, 2018
Scientific journal

Direct observation of double valence-band extrema and anisotropic effective masses of the thermoelectric material SnSe
Takanobu Nagayama; Kensei Terashima; Takanori Wakita; Hirokazu Fujiwara; Tetsushi Fukura; Yuko Yano; Kanta Ono; Hiroshi Kumigashira; Osamu Ogiso; Aichi Yamashita; Yoshihiko Takano; Hitoshi Mori; Hidetomo Usui; Masayuki Ochi; Kazuhiko Kuroki; Yuji Muraoka; Takayoshi Yokoya
JAPANESE JOURNAL OF APPLIED PHYSICS, 57, 1, Jan. 2018, Peer-reviwed
Scientific journal, English

Prediction of the High Thermoelectric Performance of Pnictogen Dichalcogenide Layered Compounds with Quasi-One-Dimensional Gapped Dirac-like Band Dispersion
Masayuki Ochi; Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW APPLIED, 8, 6, 064020-064020, Dec. 2017, Peer-reviwed
Scientific journal, English

Temperature- and doping-dependent roles of valleys in the thermoelectric performance of SnSe: A first-principles study
Hitoshi Mori; Hidetomo Usui; Masayuki Ochi; Kazuhiko Kuroki
PHYSICAL REVIEW B, 96, 8, 085113-085113, Aug. 2017, Peer-reviwed
Scientific journal, English

Intrinsic Phase Diagram of Superconductivity in the BiCh(2)-Based System Without In-Plane Disorder
Kouhei Nagasaka; Atsuhiro Nishida; Rajveer Jha; Joe Kajitani; Osuke Miura; Ryuji Higashinaka; Tatsuma D. Matsuda; Yuji Aoki; Akira Miura; Chikako Moriyoshi; Yoshihiro Kuroiwa; Hidetomo Usui; Kazuhiko Kuroki; Yoshikazu Mizuguchi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 86, 7, 074701-074701, Jul. 2017, Peer-reviwed
Scientific journal, English

Charge and quadrupole fluctuations and gap anisotropy in BiS2-based superconductors
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Hiroaki Ikeda
PHYSICAL REVIEW B, 96, 2, 024513-024513, Jul. 2017, Peer-reviwed
Scientific journal, English

Finite-energy spin fluctuations as a pairing glue in systems with coexisting electron and hole bands
Masahiro Nakata; Daisuke Ogura; Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW B, 95, 21, 214509-214509, Jun. 2017, Peer-reviwed
Scientific journal, English

Enhanced power factor and reduced Lorenz number in the Wiedemann-Franz law due to pudding mold type band structures
Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF APPLIED PHYSICS, 121, 16, 165101-165101, Apr. 2017, Peer-reviwed
Scientific journal, English

Superconductivity and Antiferromagnetic Spin Fluctuations in LaFe (As1–xPx)(O1–yFy) probed by 31P-NMR
T. Shiota; H. Mukuda; M. Uekubo; F. Engetsu; M. Yashima; Y. Kitaoka; K.T. Lai; H. Usui; K. Kuroki; S. Miyasaka; S. Tajima
Journal of Physics: Conference Series, 807, 052006, Feb. 2017, Peer-reviwed
International conference proceedings, English

High power factor in thiospinels Cu2TrTi3S8 (Tr = Mn, Fe, Co, Ni) arising from TiS6 octahedron network
Katsuaki Hashikuni; Koichiro Suekuni; Hidetomo Usui; Michihiro Ohta; Kazuhiko Kuroki; Toshiro Takabatake
APPLIED PHYSICS LETTERS, 109, 18, 182110-182110, Oct. 2016, Peer-reviwed
Scientific journal, English

Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor
Masanori Sunagawa; Kensei Terashima; Takahiro Hamada; Hirokazu Fujiwara; Tetsushi Fukura; Aya Takeda; Masashi Tanaka; Hiroyuki Takeya; Yoshihiko Takano; Masashi Arita; Kenya Shimada; Hirofumi Namatame; Masaki Taniguchi; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Takanori Wakita; Yuji Muraoka; Takayoshi Yokoya
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 85, 7, 073704-073704, Jul. 2016, Peer-reviwed
Scientific journal, English

Multiple Antiferromagnetic Spin Fluctuations and Novel Evolution of T-c in Iron-Based Superconductors LaFe(As1-xPx)(O1-yFy) Revealed by P-31-NMR Studies
Takayoshi Shiota; Hidekazu Mukuda; Masahiro Uekubo; Fuko Engetsu; Mitsuharu Yashima; Yoshio Kitaoka; Kwing To Lai; Hidetomo Usui; Kazuhiko Kuroki; Shigeki Miyasaka; Setsuko Tajima
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 85, 5, 053706-053706, May 2016, Peer-reviwed
Scientific journal, English

Comparative ARPES studies of LaOxF1-xBiS2 (x = 0.23 and 0.46)
K. Terashima; T. Wakita; M. Sunagawa; H. Fujiwara; T. Nagayama; K. Ono; H. Kumigashira; M. Nagao; S. Watauchi; I. Tanaka; H. Okazaki; Y. Takano; Y. Mizuguchi; H. Usui; K. Kuroki; Y. Muraoka; T. Yokoya
Journal of Physics: Conference Series, 683, 1, 05 Feb. 2016, Peer-reviwed
International conference proceedings

Bulk sensitive angle-resolved photoelectron spectroscopy on Nd(O,F)BiS2
K. Terashima; J. Sonoyama; M. Sunagawa; H. Fujiwara; T. Nagayama; T. Muro; M. Nagao; S. Watauchi; I. Tanaka; H. Okazaki; Y. Takano; Y. Mizuguchi; H. Usui; K. Suzuki; K. Kuroki; T. Wakita; Y. Muraoka; T. Yokoya
TMU INTERNATIONAL SYMPOSIUM ON NEW QUANTUM PHASES EMERGING FROM NOVEL CRYSTAL STRUCTURE, 683, 0012003, 2016, Peer-reviwed
International conference proceedings, English

22aBL-5 Correlation between finite-energy spin fluctuation and T_c in hole- and electron-Fermi surface system
Nakata Masahiro; Ogura Daisuke; Usui Hidetomo; Kuroki Kazuhiko
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 71, 2352-2352, 2016
Japanese

22aBN-8 Understanding of the anisotropic gap symmetry from orbital fluctuation mechanism in the BiS_2 based superconductors
Suzuki K.; Usui H.; Kuroki K.; Ikeda H.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 71, 2379-2379, 2016
Japanese

22aBN-11 First principles analysis of the power factor in thermoelectric material BiCuSeO
Usui H.; Kuroki K.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 71, 2381-2381, 2016
Japanese

19aBP-1 ARPES study on thermoelectric material SnSe
Nagayama T.; Terashima K.; Tanaka M.; Ogiso O.; Takano Y.; Mori H.; Usui H.; Kuroki K.; Wakita T.; Muraoka Y.; Yokoya T.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 71, 1441-1441, 2016
Japanese

Electronic structure of AxFe2-ySe2 (A=K,Rb) studied by angle-resolved photoemission spectroscopy
Sunagawa M.; Terashima K.; Fujiwara H.; Fukura T.; Takeda A.; Tanaka M.; Takeya H.; Takano Y.; Arita M.; Shimada K.; Namatame H.; Taniguchi M.; Suzuki K.; Usui H.; Kuroki K.; Wakita T.; Muraoka Y.; Yokoya T.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 71, 2023-2023, 2016,

A_x_Fe_2-y_Se_2_(A=K,Rb)はTc~30Kを発現する鉄系超伝導体であり、角度分解光電子分光(ARPES)先行研究では電子フェルミ面のみが観測されている。今回我々は、高品質Rb_x_Fe_2-y_Se_2_単結晶を用いたARPES実験を行い、バンドの上端がフェルミエネルギー近傍に達するホールバンドを示唆する結果を得た。本講演ではこのホールバンドの起源と超伝導との関連性について議論する。

Japanese

The origin of high power factor of n- and p- type SnSe from first principles calculations
Mori Hitoshi
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 71, 1738-1738, 2016,

最近、半導体の一つであるSnSeで、無次元性能指数ZT=2.6という高い熱電効果が実験的に報告され、それ以来、SnSeに対する研究は精力的に行われている。我々の研究では、第一原理バンド計算およびBoltzmann方程式を用いて、SnSeの電気伝導度やSeebeck係数などの評価を行い、概ね実験を再現するような結果を得ることができた。その後、キャリアドープを仮想的に行った場合についても計算を行い、ZTを上昇させるいくつかの可能性を示唆する結果を得た。今回の発表では、それらの結果を紹介するとともに、理論的背景についても述べる。

Japanese

³¹P-NMR study in iron-based superconductor LaFe(As_1-xP_x)(O_1-yH_y)
Shiota T.; Mukuda H.; Yashima M.; Kitaoka Y.; Uekubo M.; Usui H.; Kuroki K.; Lai K. T.; Miyasaka S.; Tajima S.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 71, 1835-1835, 2016,

鉄系超伝導体LaFe(As_1-x_P_x_)(O_1-y_H_y_)においてNMRを行い、この系での超伝導と磁性、および結晶構造因子との関係を議論する予定である。これまでのLaFe(As_1-x_P_x_)(O_1-y_F_y_)系の結果と比較する。

Japanese

Minimal Electronic Model for a Layered Nitride Halide Superconductor beta-ZrNCl
Hiroshi Tanaka; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 84, 12, 124706-124706, Dec. 2015, Peer-reviwed
Scientific journal, English

Theoretical aspects of the study of the new bismuth chalcogenide based superconductors
H. Usui; K. Kuroki
Novel Superconducting Materials, 1, 50-63 (invited review), Nov. 2015, Peer-reviwed
Scientific journal, English

Origin of the non-monotonic variance of T-c in the 1111 iron based superconductors with isovalent doping
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki
SCIENTIFIC REPORTS, 5, 11399-11399, Jun. 2015, Peer-reviwed
Scientific journal, English

Theoretical study of correlation between spin fluctuations and T-c in isovalent-doped 1111 iron-based superconductors
Hayato Arai; Hidetomo Usui; Katsuhiro Suzuki; Yuki Fuseya; Kazuhiko Kuroki
PHYSICAL REVIEW B, 91, 13, 134511-134511, Apr. 2015, Peer-reviwed
Scientific journal, English

Theoretical aspects of the study on the new bismuth chalcogenide based superconductors
Usui, Hidetomo; Kuroki, Kazuhiko
Nov. Supercond. Mater., DE GRUYTER, 1, 1, 50-50, 2015
Scientific journal

17aPS-101 Effect of spin-orbit coupling in BiS_2 superconductors
Suzuki K.; Usui H.; Kuroki K.; Ikeda H.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 70, 1894-1894, 2015
Japanese

16aDB-6 Angle-resolved photoemission spectroscopy on KxFe_<2-y>Se_2 II
Sunagawa M.; Terashima K.; Hamada K.; Fujiwara H.; Fukura T.; Takeda A.; Tanaka M.; Takeya H.; Takano Y.; Arita M.; Shimada K.; Namatame H.; Taniguchi M.; Suzuki K.; Usui H.; Kuroki K.; Wakita T.; Muraoka Y.; Yokoya T.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 70, 1681-1681, 2015
Japanese

16pDA-7 Relationship between Fermi surface topology and chemical pressure effect on Ln(O,F)BiS_2 studied by ARPES
Terashima K.; Wakita T.; Sunagawa M.; Fujiwara H.; Hamada T.; Nagao M.; Watauchi S.; Tanaka I.; Ono K.; Kumigashira H.; Okazaki H.; Takano Y.; Usui H.; Kuroki K.; Suzuki K.; Muraoka Y.; Yokoya T.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 70, 1720-1720, 2015
Japanese

21pBA-12 Observation of hole-like Fermi surface in K_xFe_<2-y>Se_2
Sunagawa M.; Terashima K.; Hamada K.; Fujiwara H.; Tanaka M.; Takeya H.; Takano Y.; Arita M.; Shimada K.; Namatame H.; Taniguchi M.; Suzuki K.; Usui H.; Kuroki K.; Wakita T.; Muraoka Y.; Yokoya T.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 70, 1997-1997, 2015
Japanese

22aBE-10 Perspective understanding of the iron-based superconductors from the viewpoint of prioritized diagonal motion of electrons
Suzuki K.; Usui H.; Kuroki K.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan (JPS), 70, 2096-2096, 2015
Japanese

24aPS-29 Study of spin and charge fluctuation in a model of β-MNCl based on first principles calculation
Tanaka Hiroshi; Suzuki Katsuhiro; Usui Hidetomo; Kuroki Kazuhiko
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 70, 0, 2382-2382, 2015, Peer-reviwed
Japanese

Proximity to Fermi-surface topological change in superconducting LaO0.54F0.46BiS2
Kensei Terashima; Junki Sonoyama; Takanori Wakita; Masanori Sunagawa; Kanta Ono; Hiroshi Kumigashira; Takayuki Muro; Masanori Nagao; Satoshi Watauchi; Isao Tanaka; Hiroyuki Okazaki; Yoshihiko Takano; Osuke Miura; Yoshikazu Mizuguchi; Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki; Yuji Muraoka; Takayoshi Yokoya
PHYSICAL REVIEW B, 90, 22, 220512-220512, Dec. 2014, Peer-reviwed
Scientific journal, English

Model of the Electronic Structure of Electron-Doped Iron-Based Superconductors: Evidence for Enhanced Spin Fluctuations by Diagonal Electron Hopping
Katsuhiro Suzuki; Hidetomo Usui; Soshi Iimura; Yoshiyasu Sato; Satoru Matsuishi; Hideo Hosono; Kazuhiko Kuroki
PHYSICAL REVIEW LETTERS, 113, 2, 027002-027002, Jul. 2014, Peer-reviwed
Scientific journal, English

Orbital mixture effect on the Fermi-surface–Tccorrelation in the cuprate superconductors: Bilayer vs. single layer
Hirofumi Sakakibara; Katsuhiro Suzuki; Hidetomo Usui; Satoaki Miyao; Isao Maruyama; Koichi Kusakabe; Ryotaro Arita; Hideo Aoki; Kazuhiko Kuroki
Physical Review B, American Physical Society (APS), 89, 22, 09 Jun. 2014, Peer-reviwed
Scientific journal

Pudding-Mold-Type Band as an Origin of the Large Seebeck Coefficient Coexisting with Metallic Conductivity in Carrier-Doped FeAs2 and PtSe2
Hidetomo Usui; Kazuhiko Kuroki; Seiya Nakano; Kazutaka Kudo; Minoru Nohara
JOURNAL OF ELECTRONIC MATERIALS, 43, 6, 1656-1661, Jun. 2014, Peer-reviwed
Scientific journal, English

Orbital mixture effect on the Fermi-surface-T-c correlation in the cuprate superconductors: Bilayer vs. single layer
Hirofumi Sakakibara; Katsuhiro Suzuki; Hidetomo Usui; Satoaki Miyao; Isao Maruyama; Koichi Kusakabe; Ryotaro Arita; Hideo Aoki; Kazuhiko Kuroki
PHYSICAL REVIEW B, 89, 22, 224505-224505, Jun. 2014, Peer-reviwed
Scientific journal, English

Soft X-ray Photoemission Study of New BiS2-Layered Superconductor LaO1-xFxBiS2
Shinsuke Nagira; Junki Sonoyama; Takanori Wakita; Masanori Sunagawa; Yudai Izumi; Takayuki Muro; Hiroshi Kumigashira; Masaharu Oshima; Keita Deguchi; Hiroyuki Okazaki; Yoshihiko Takano; Osuke Miura; Yoshikazu Mizuguchi; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Kozo Okada; Yuji Muraoka; Takayoshi Yokoya
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 83, 3, 033703-033703, Mar. 2014, Peer-reviwed
Scientific journal, English

Theoretical Expectation of Large Seebeck Effect in PtAs2 and PtP2
Kouta Mori; Hidetomo Usui; Hirofumi Sakakibara; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 83, 2, 023706-023706, Feb. 2014, Peer-reviwed
Scientific journal, English

Theoretical analysis on the band structure variance of the electron doped 1111 iron-based superconductors
K. Suzuki; H. Usui; S. Iimura; Y. Sato; S. Matsuishi; H. Hosono; K. Kuroki
PROCEEDINGS OF THE 26TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2013), 58, 38-41, 2014, Peer-reviwed
International conference proceedings, English

30pCE-9 Enhancement of superconductivity and spin fluctuation due to the positive charge within the blocking layers in the iron-based superconductors
Suzuki K.; Sakakibara H.; Usui H.; Kuroki K.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 69, 0, 678-678, 2014, Peer-reviwed
Japanese

30aCG-7 Multiple enhancement mechanisms of the dynamical spin fluctuation in the iron based superconductors
Arai Hayato; Suzuki Katsuhiro; Usui Hidetomo; Fuseya Yuki; Kuroki Kazuhiko
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 69, 0, 669-669, 2014, Peer-reviwed
Japanese

30aCG-4 Five-orbital-model analysis on the superconducting transition temperature of the hydrogen-doped iron pnictide superconductors
Sakakibara H.; Suzuki K.; Usui H.; Kuroki K.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 69, 0, 668-668, 2014, Peer-reviwed
Japanese

28apS-141 Effective model for BaTi_2Sb_2O and its analysis based on first-principles band-structure calculation
Mori K.; Sakakibara H.; Suzuki K.; Usui H.; Kuroki K.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 69, 0, 625-625, 2014, Peer-reviwed
Japanese

Theoretical study of the chemical pressure effect on T-c in the cuprate superconductors
H. Sakakibara; K. Suzuki; H. Usui; K. Kuroki; R. Arita; H. Aoki
PROCEEDINGS OF THE 26TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2013), 58, 34-37, 2014, Peer-reviwed
International conference proceedings, English

Switching of intra-orbital spin excitations in electron-doped iron pnictide superconductors
Soshi Iimura; Satoru Matsuishi; Masashi Miyakawa; Takashi Taniguchi; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Ryoichi Kajimoto; Mitsutaka Nakamura; Yasuhiro Inamura; Kazuhiko Ikeuchi; Sungdae Ji; Hideo Hosono
PHYSICAL REVIEW B, 88, 6, 060501-060501, Aug. 2013, Peer-reviwed
Scientific journal, English

Robust Spin Fluctuations and s +/- Pairing in the Heavily Electron Doped Iron-Based Superconductors
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Soshi Iimura; Yoshiyasu Sato; Satoru Matsuishi; Hideo Hosono
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 82, 8, 083702-083702, Aug. 2013, Peer-reviwed
Scientific journal, English

Switching of intra-orbital spin excitations in electron-doped iron pnictide superconductors
Soshi Iimura; Satoru Matsuishi; Masashi Miyakawa; Takashi Taniguchi; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Ryoichi Kajimoto; Mitsutaka Nakamura; Yasuhiro Inamura; Kazuhiko Ikeuchi; Sungdae Ji; Hideo Hosono
Physical Review B - Condensed Matter and Materials Physics, 88, 6, 01 Aug. 2013, Peer-reviwed
Scientific journal, English

Large Seebeck effect in electron-doped FeAs2 driven by a quasi-one-dimensional pudding-mold-type band
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki; Seiya Nakano; Kazutaka Kudo; Minoru Nohara
PHYSICAL REVIEW B, 88, 7, 075140-075140, Aug. 2013, Peer-reviwed
Scientific journal, English

Ideal band shape in the potential thermoelectric material CuAlO2: Comparison to NaxCoO2
Kouta Mori; Hirofumi Sakakibara; Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW B, 88, 7, 075141-075141, Aug. 2013, Peer-reviwed
Scientific journal, English

Understanding the reentrant superconducting phase diagram of the iron pnictide Ca4Al2O6Fe2(As1-xPx)(2): First-principles calculations
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki; Nao Takeshita; Parasharam Maruti Shirage; Hiroshi Eisaki; Akira Iyo
PHYSICAL REVIEW B, 87, 17, 174528-174528, May 2013, Peer-reviwed
Scientific journal, English

Minimum model and its theoretical analysis for superconducting materials with BiS2 layers
Suzuki, Katsuhiro; Usui, Hidetomo; Kuroki, Kazuhiko
Physics Procedia, Elsevier, 45, 21-24, 2013
Scientific journal

Pudding-mold type band in a potential thermoelectric material CuAlO $ _2 $: comparison with Na $ _x $ CoO $ _2$
Mori, Kouta; Sakakibara; Hirofumi; Usui, Hidetomo; Kuroki, Kazuhiko
arXiv preprint arXiv:1304.2526, 2013
Scientific journal

Three-orbital study on the orbital distillation effect in the high T c cuprates
H. Sakakibara; K. Suzuki; H. Usui; K. Kuroki; R. Arita; D. J. Scalapino; H. Aokid
Physics Procedia, Elsevier B.V., 45, 13-16, 2013, Peer-reviwed
International conference proceedings, English

27pXJ-9 Orbital distillation effects of Cu-4s orbital in cuprates
Sakakibara H.; Suzuki K.; Usui H.; Kuroki K.; Arita R.; Scalapino D. J.; Aoki H.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 68, 0, 656-656, 2013, Peer-reviwed
Japanese

First-principles band structure and FLEX approach to the pressure effect on T-c of the cuprate superconductors
Hirofumi Sakakibara; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Douglas J. Scalapino; Hideo Aoki
24TH IUPAP CONFERENCE ON COMPUTATIONAL PHYSICS (IUPAP-CCP 2012), 454, 2013, Peer-reviwed
International conference proceedings, English

BiS2-based layered superconductor Bi4O 4S3
Yoshikazu Mizuguchi; Hiroshi Fujihisa; Yoshito Gotoh; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Satoshi Demura; Yoshihiko Takano; Hiroki Izawa; Osuke Miura
Physical Review B - Condensed Matter and Materials Physics, 86, 22, 26 Dec. 2012, Peer-reviwed
Scientific journal, English

Minimal electronic models for superconducting BiS2 layers
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki
Physical Review B - Condensed Matter and Materials Physics, 86, 22, 03 Dec. 2012, Peer-reviwed
Scientific journal, English

Minimal electronic models for superconducting BiS2 layers
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki
PHYSICAL REVIEW B, 86, 22, 220501-220501, Dec. 2012, Peer-reviwed
Scientific journal, English

BiS2-based layered superconductor Bi4O4S3
Yoshikazu Mizuguchi; Hiroshi Fujihisa; Yoshito Gotoh; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Satoshi Demura; Yoshihiko Takano; Hiroki Izawa; Osuke Miura
PHYSICAL REVIEW B, 86, 22, 220510-220510, Dec. 2012, Peer-reviwed
Scientific journal, English

Corrugated flat band as an origin of large thermopower in hole doped PtSb2
Kouta Mori; Hidetomo Usui; Hirofumi Sakakibara; Kazuhiko Kuroki
AIP ADVANCES, 2, 4, 042108-042108, Dec. 2012, Peer-reviwed
Scientific journal, English

Multiorbital analysis of the effects of uniaxial and hydrostatic pressure on T-c in the single-layered cuprate superconductors
Hirofumi Sakakibara; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Douglas J. Scalapino; Hideo Aoki
PHYSICAL REVIEW B, 86, 13, 134520-134520, Oct. 2012, Peer-reviwed
Scientific journal, English

Least momentum space frustration as a condition for a 'high T-c sweet spot' in iron-based superconductors
Hidetomo Usui; Katsuhiro Suzuki; Kazuhiko Kuroki
SUPERCONDUCTOR SCIENCE & TECHNOLOGY, 25, 8, 084004-084004, Aug. 2012, Peer-reviwed
Scientific journal, English

Origin of the material dependence of T-c in the single-layered cuprates
Hirofumi Sakakibara; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Hideo Aoki
PHYSICAL REVIEW B, 85, 6, 064501-064501, Feb. 2012, Peer-reviwed
Scientific journal, English

Origin of the material dependence of T c in the single-layered cuprates
Sakakibara, H.; Usui, H.; Kuroki, K.; Arita, R.; Aoki, H.
Physical Review B - Condensed Matter and Materials Physics, 85, 6, 2012, Peer-reviwed
Scientific journal

The origin of the electron-hole asymmetry of the spin fluctuation and its effect on superconductivity in iron-based superconductors
K. Suzuki; H. Usui; K. Kuroki
Journal of Physics: Conference Series, Institute of Physics Publishing, 400, 2, 2012, Peer-reviwed
International conference proceedings, English

20aGB-1 Orbital distillation effect on Tc induced by external pressures in HTC cuprates
Sakakibara H.; Suzuki K.; Usui H.; Kuroki K.; Arita R.; Scalapino D. J.; Aoki H.
Meeting Abstracts of the Physical Society of Japan, The Physical Society of Japan, 67, 0, 503-503, 2012, Peer-reviwed
Japanese

Effective five band analysis on T-c vs. lattice structure correlation in iron pnictides
Hidetomo Usui; Kazuhiko Kuroki
26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5, 400, 2012, Peer-reviwed
International conference proceedings, English

Two-orbital view on the origin of the material dependence of T-c in the single-layer cuprates
Hirofumi Sakakibara; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Hideo Aoki
26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5, 400, 2012, Peer-reviwed
International conference proceedings, English

Theoretical analysis for inelastic neutron scattering on BaFe 2(As 1-xP x) 2 using realistic three-dimensional 10-orbital tight-binding model
Y. Nagai; H. Nakamura; K. Suzuki; H. Usui; K. Kuroki; M. Machida
Journal of the Physical Society of Japan, The Physical Society of Japan, 80, SUPPL. B, SB021\_1-SB021\_4, Dec. 2011, Peer-reviwed
International conference proceedings, English

Spin fluctuations and unconventional pairing in KFe2As 2
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki
Physical Review B - Condensed Matter and Materials Physics, APS, 84, 14, 144514-144514, 14 Oct. 2011, Peer-reviwed
Scientific journal, English

Spin fluctuations and unconventional pairing in KFe2As2
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW B, 84, 14, Oct. 2011, Peer-reviwed
Scientific journal, English

s(+/-)-like spin resonance in the iron-based nodal superconductor BaFe2(As0.65P0.35)(2) observed using inelastic neutron scattering
Motoyuki Ishikado; Yuki Nagai; Katsuaki Kodama; Ryoichi Kajimoto; Mitsutaka Nakamura; Yasuhiro Inamura; Shuichi Wakimoto; Hiroki Nakamura; Masahiko Machida; Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki; Akira Iyo; Hiroshi Eisaki; Masatoshi Arai; Shin-ichi Shamoto
PHYSICAL REVIEW B, 84, 14, 144517-144517, Oct. 2011, Peer-reviwed
Scientific journal, English

Maximizing the Fermi-surface multiplicity optimizes the superconducting state of iron pnictide compounds
Hidetomo Usui; Kazuhiko Kuroki
PHYSICAL REVIEW B, 84, 2, 024505-024505, Jul. 2011, Peer-reviwed
Scientific journal, English

Incommensurate spin fluctuations in hole-overdoped superconductor KFe 2As2
C. H. Lee; K. Kihou; H. Kawano-Furukawa; T. Saito; A. Iyo; H. Eisaki; H. Fukazawa; Y. Kohori; K. Suzuki; H. Usui; K. Kuroki; K. Yamada
Physical Review Letters, APS, 106, 6, 067003-067003, 11 Feb. 2011, Peer-reviwed
Scientific journal, English

Possible Three-Dimensional Nodes in the s +/- Superconducting Gap of BaFe2(As1-xPx)(2)
Katsuhiro Suzuki; Hidetomo Usui; Kazuhiko Kuroki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 80, 1, 013710-013710, Jan. 2011, Peer-reviwed
Scientific journal, English

Pnictogen height as a switch between high-T-c nodeless and low-T-c nodal pairings in the iron-based superconductors
Kazuhiko Kuroki; Hidetomo Usui; Seiichiro Onari; Ryotaro Arita; Hideo Aoki
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 470, S416-S417, Dec. 2010, Peer-reviwed
Scientific journal, English

Effective five band analysis on the pressure effect of FeSe
Hidetomo Usui; Kazuhiko Kuroki
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS, 470, S382-S384, Dec. 2010, Peer-reviwed
Scientific journal, English

Enhancement of the Nax CoO2 thermopower due to electronic correlations
P. Wissgott; A. Toschi; H. Usui; K. Kuroki; K. Held
Physical Review B - Condensed Matter and Materials Physics, APS, 82, 20, 201106-201106, 30 Nov. 2010, Peer-reviwed
Scientific journal, English

Two-Orbital Model Explains the Higher Transition Temperature of the Single-Layer Hg-Cuprate Superconductor Compared to That of the La-Cuprate Superconductor
Hirofumi Sakakibara; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Hideo Aoki
PHYSICAL REVIEW LETTERS, 105, 5, 057003-057003, Jul. 2010, Peer-reviwed
Scientific journal, English

Origin of coexisting large Seebeck coefficient and metallic conductivity in the electron doped SrTiO3 and KTaO3
Hidetomo Usui; Shinsuke Shibata; Kazuhiko Kuroki
PHYSICAL REVIEW B, 81, 20, 205121-205121, May 2010, Peer-reviwed
Scientific journal, English

Pnictogen height as a possible switch between high-T-c nodeless and low-T-c nodal pairings in the iron-based superconductors
Kazuhiko Kuroki; Hidetomo Usui; Seiichiro Onari; Ryotaro Arita; Hideo Aoki
PHYSICAL REVIEW B, 79, 22, 224511-224511, Jun. 2009, Peer-reviwed
Scientific journal, English

Unconventional Pairing Originating from the Disconnected Fermi Surfaces of Superconducting LaFeAsO1-xFx (vol 101, 087004, 2008)
Kazuhiko Kuroki; Seiichiro Onari; Ryotaro Arita; Hidetomo Usui; Yukio Tanaka; Hiroshi Kontani; Hideo Aoki
PHYSICAL REVIEW LETTERS, 102, 10, 109902-109902, Mar. 2009, Peer-reviwed
Scientific journal, English

First-principles study on the origin of large thermopower in hole-doped LaRhO3 and CuRhO2
Hidetomo Usui; Ryotaro Arita; Kazuhiko Kuroki
JOURNAL OF PHYSICS-CONDENSED MATTER, 21, 6, Feb. 2009, Peer-reviwed
Scientific journal, English

Unconventional pairing originating from disconnected Fermi surfaces in the iron-based superconductor
Kazuhiko Kuroki; Seiichiro Onari; Ryotaro Arita; Hidetomo Usui; Yukio Tanaka; Hiroshi Kontani; Hideo Aoki
NEW JOURNAL OF PHYSICS, 11, Feb. 2009, Peer-reviwed
Scientific journal, English

Minimal model for study on Superconductivity in LaFeAsO1-xFx based on ab-initio downfolding
Ryotaro Arita; Seiichiro Onari; Hidetomo Usui; Kazuhiko Kuroki; Yukio Tanaka; Hiroshi Kontani; Hideo Aoki
25TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT25), PART 5, 150, 2009, Peer-reviwed
International conference proceedings, English

Study on the origin of large thermopower in hole doped LaRhO3 based on ab-initio downfolding
Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita
25TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT25), PART 2, 150, 2009, Peer-reviwed
International conference proceedings, English

Photoemission Study of the Electronic Structure of LaFeAsO1-xFx and LaFePO1-xFx
Walid Malaeb; Teppei Yoshida; Takashi Kataoka; Atsushi Fujimori; Masato Kubota; Kanta Ono; Hidetomo Usui; Kazuhiko Kuroki; Ryotaro Arita; Hideo Aoki; Yoichi Kamihara; Masahiro Hirano; Hideo Hosono
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 77, Suppl. C, 69-71, Nov. 2008, Peer-reviwed
Scientific journal, English

Unconventional superconductivity originating from disconnected Fermi surfaces in the iron-based oxypnictide
Kazuhiko Kuroki; Seiichiro Onari; Ryotaro Arita; Hidetomo Usui; Yukio Tanaka; Hiroshi Kontani; Hideo Aoki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 77, Suppl. C, 96-98, Nov. 2008, Peer-reviwed
Scientific journal, English

Unconventional pairing originating from the disconnected Fermi surfaces of superconducting LaFeAsO1-xFx
Kazuhiko Kuroki; Seiichiro Onari; Ryotaro Arita; Hidetomo Usui; Yukio Tanaka; Hiroshi Kontani; Hideo Aoki
PHYSICAL REVIEW LETTERS, 101, 8, 087004-087004, Aug. 2008, Peer-reviwed
Scientific journal, English

Unified origin for superconductivity, magnetism, and large thermopower in Nax CoO2
Kuroki, K.; Arita, R.; Okubo, S.; Nojima, T.; Usui, H.; Onari, S.; Tanaka, Y.
Journal of Physics and Chemistry of Solids, Pergamon, 69, 12, 3360-3364, 2008, Peer-reviwed
Scientific journal

Unified origin for superconductivity and 3D magnetism in Nax CoO2
Kuroki, K.; Okubo, S.; Nojima, T.; Usui, H.; Arita, R.; Onari, S.; Tanaka, Y.
Physica B: Condensed Matter, North-Holland, 403, 5-9, 1151-1153, 2008, Peer-reviwed
Scientific journal

LnOBi(S,Se)₂の結晶構造とバンド構造の相関関係
臼井秀知; 有田亮太郎; 黒木和彦
2015, 日本物理学会講演概要集(CD-ROM), 70, 1, 2189-079X, 201502201546038195

Bi(S,Se)₂系超伝導体のトポロジー解析
臼井秀知; 有田亮太郎; 黒木和彦
2015, 日本物理学会講演概要集(CD-ROM), 70, 2, 2189-079X, 201602201456649346

9aBD-13 Study on the correlation between s± pairing and intra-orbital spin fluctuations in 1111 iron based superconductors with isovalent doping
Usui H.; Suzuki K.; Kuroki K.
The Physical Society of Japan (JPS), 22 Aug. 2014, Meeting abstracts of the Physical Society of Japan, 69, 2, 399-399, Japanese, 1342-8349, 110009887646, AA11439205

7aBH-6 Importance of Prioritized Diagonal Motion of electrons in iron-based superconductors
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 22 Aug. 2014, Meeting abstracts of the Physical Society of Japan, 69, 2, 325-325, Japanese, 1342-8349, 110009887367, AA11439205

27pPSA-31 NMR relaxation rate of the horizontal node superconducting state in the iron-based superconductor SrFe_2(As,P)_2
Matsushima K.; Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 05 Mar. 2014, Meeting abstracts of the Physical Society of Japan, 69, 1, 570-570, Japanese, 1342-8349, 110009835605, AA11439205

30pCE-8 Study on the correlation between the band dispersion, spin fluctuations and superconductivity in LaFe(As_<1-x>P_x)O
Usui H.; Suzuki K.; Kuroki K.
The Physical Society of Japan (JPS), 05 Mar. 2014, Meeting abstracts of the Physical Society of Japan, 69, 1, 678-678, Japanese, 1342-8349, 110009836013, AA11439205

28pBE-3 First principles calculation and model Hamiltonian analysis of BiS_2 superconductors
Usui Hidetomo
The Physical Society of Japan (JPS), 05 Mar. 2014, Meeting abstracts of the Physical Society of Japan, 69, 1, 627-627, Japanese, 1342-8349, 110009835829, AA11439205

Ab initio band calculation and effective model construction of β"-(DODHT)_2XF6(X=P,As)
Tanaka H.; Suzuki K.; Usui H.; Aizawa H.; Kuroki K.
The Physical Society of Japan (JPS), 26 Aug. 2013, Meeting abstracts of the Physical Society of Japan, 68, 2, 745-745, Japanese, 1342-8349, 110009756032, AA11439205

Theoretical study on the origin of large thermopower in PtSe_2
Usui H.; Kuroki K.; Kudo K.; Nakano S.; Nohara M.
The Physical Society of Japan (JPS), 26 Aug. 2013, Meeting abstracts of the Physical Society of Japan, 68, 2, 576-576, Japanese, 1342-8349, 110009757350, AA11439205

Theoretical analysis of s_± pairing mediated by incommensurate spin fluctuation in heavily electron-doped 1111 iron-based superconductors
Suzuki K.; Usui H.; Kuroki K.; Iimura S.; Sato Y.; Matsuishi M.; Hosono H.
The Physical Society of Japan (JPS), 26 Aug. 2013, Meeting abstracts of the Physical Society of Japan, 68, 2, 576-576, Japanese, 1342-8349, 110009757348, AA11439205

29aXX-6 Pnictogen-dependence of the Seebeck effect in PtX_2(X=Sb,As,P)
Mori K.; Usui H.; Sakakibara H.; Kuroki K.
The Physical Society of Japan (JPS), 26 Mar. 2013, Meeting abstracts of the Physical Society of Japan, 68, 1, 694-694, Japanese, 1342-8349, 110009644931, AA11439205

27aXZE-2 Inelastic neutron scattering of magnetic excitations on LaFeAsO_<1-x>D_x
Iimura S.; Matsuishi S.; Miyakawa M.; Taniguchi T.; Kajimoto R.; Nakamura M.; Ikeuchi K.; Ji Sungdae; Suzuki K.; Usui H.; Kuroki K.; Hosono H.
The Physical Society of Japan (JPS), 26 Mar. 2013, Meeting abstracts of the Physical Society of Japan, 68, 1, 606-606, Japanese, 1342-8349, 110009644609, AA11439205

27aXZE-4 The theoretical analysis based on spin fluctuation for electron-doped iron-pnictide superconductor LaFeAsO_<1-x>H_x
Suzuki K.; Usui H.; Kuroki K.; Iimura S.; Matsuishi S.; Hosono H.
The Physical Society of Japan (JPS), 26 Mar. 2013, Meeting abstracts of the Physical Society of Japan, 68, 1, 607-607, Japanese, 1342-8349, 110009644611, AA11439205

26pXY-6 Minimum model construction from first principles band calculation in BiS_2 layered materials
Usui H.; Suzuki K.; Kuroki K.
The Physical Society of Japan (JPS), 26 Mar. 2013, Meeting abstracts of the Physical Society of Japan, 68, 1, 591-591, Japanese, 1342-8349, 110009644549, AA11439205

元素置換された銅酸化物における化学的圧力による超伝導最適化の可能性
榊原寛史; 鈴木雄大; 臼井秀知; 黒木和彦; 有田亮太郎; 有田亮太郎; 青木秀夫
2013, 日本物理学会講演概要集, 68, 2, 1342-8349, 201302249160941416

18pFF-16 The contribution of the k-space frustrations for superconducting gap structure in LiFe(As,P)
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 460-460, Japanese, 1342-8349, 110009600138, AA11439205

18pFF-15 Study on the competition between anti-ferromagnetism and superconductivity in Ca_4Al_2O_6Fe_2(As_<1-x>P_x)_2
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 459-459, Japanese, 1342-8349, 110009600137, AA11439205

20pFE-16 Corrugated flat band as an origin of the large Seebeck effect in doped PtSt_2
Mori K.; Sakakibara H.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 798-798, Japanese, 1342-8349, 110009601410, AA11439205

20pFE-14 Study on the origin of thermopower in FeAs_2 based on ab-initio calculation
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 797-797, Japanese, 1342-8349, 110009601408, AA11439205

20pFE-16 Corrugated flat band as an origin of the large Seebeck effect in doped PtSb_2
Mori K.; Sakakibara H.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 543-543, Japanese, 1342-8349, 110009600454, AA11439205

20pFE-14 Study on the origin of thennopower in FeAs_2 based on ab-initio calculation
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 542-542, Japanese, 1342-8349, 110009600452, AA11439205

20pGA-17 Superconducting properties and mechanism of novel layered superconducting family
Takano Yoshihiko; Mizuguchi Yoshikazu; Demura Satoshi; Deguchi Keita; Fujihisa Hiroshi; Gotoh Yoshito; Izawa Hiroki; Miura Osuke; Suzuki Katsuhiro; Usui Hidetomo; Kuroki Kazuhiko
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 554-554, Japanese, 1342-8349, 110009600498, AA11439205

20pFE-15 Possibility of large Seebeck effect due to a pudding mold type band structure in CuAlO_2
Mori K.; Sakakibara H.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67, 2, 542-542, Japanese, 1342-8349, 110009600453, AA11439205

25pYH-1 Mechanisms of the T_c suppression due to d_z^2 orbital mixing in the high T_c cuprates
Sakakibara H.; Usui H.; Kuroki K.; Arita R.; Aoki H.
The Physical Society of Japan (JPS), 05 Mar. 2012, Meeting abstracts of the Physical Society of Japan, 67, 1, 646-646, Japanese, 1342-8349, 110009567196, AA11439205

27aYA-3 The contribution of the three dimensional orbital hybridization for superconductivity in the iron based superconductors
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 05 Mar. 2012, Meeting abstracts of the Physical Society of Japan, 67, 1, 678-678, Japanese, 1342-8349, 110009567313, AA11439205

25aYD-4 Study on the large thermopower originating from spin fluctuations in Na_xCoO_2
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 05 Mar. 2012, Meeting abstracts of the Physical Society of Japan, 67, 1, 589-589, Japanese, 1342-8349, 110009566991, AA11439205

銅酸化物におけるd_A(A=x²)軌道混成による超伝導抑制メカニズム
榊原寛史; 臼井秀知; 黒木和彦; 有田亮太郎; 有田亮太郎; 有田亮太郎; 青木秀夫; 青木秀夫
2012, 日本物理学会講演概要集, 67, 1, 1342-8349, 201202213482866019

23aGM-8 The origin of the electoron-hole asymmetry of the spin fluctuation incommensurability in the iron pnictide superconductors
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2011, Meeting abstracts of the Physical Society of Japan, 66, 2, 575-575, Japanese, 1342-8349, 110008759348, AA11439205

23aGM-7 Five band model study on the lattice structure effect on the T_c of iron pnictides
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 24 Aug. 2011, Meeting abstracts of the Physical Society of Japan, 66, 2, 575-575, Japanese, 1342-8349, 110008759347, AA11439205

鉄系超伝導体La1111系及びBaFe_2(As,P)_2の磁気散乱(鉄系高温超伝導の物理,研究会報告)
石角 元志; 永井 佑紀; 樹神 克明; 梶本 亮一; 中村 充孝; 稲村 泰弘; 水野 文夫; 脇本 秀一; 中村 博樹; 町田 昌彦; 鈴木 雄大; 臼井 秀知; 黒木 和彦; 伊豫 彰; 永崎 洋; 新井 正敏; 社本 真一
物性研究刊行会, 05 Aug. 2011, 物性研究, 96, 5, 574-574, Japanese, 0525-2997, 110008712506, AN0021948X

25pEE-1 The origin of the elertoron-hole asymmetry of the spin fluctuations and superconductivity in the iron pnictide supercpnductors
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66, 1, 556-556, Japanese, 1342-8349, 110008714253, AA11439205

25pEE-2 Study on the effect of small bond angle in the iron puictides
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66, 1, 556-556, Japanese, 1342-8349, 110008714254, AA11439205

26pEE-13 The possibility of superconductivity by tuning the condition of the crystal field in a perovskite superlattice nickelate LaAlO_3/LaNiO_3
Sakakibara H.; Usui H.; Kuroki K.; Aoki H.
The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66, 1, 606-606, Japanese, 1342-8349, 110008714441, AA11439205

鉄系超伝導体における結晶構造と臨界温度の相関の起源(鉄系高温超伝導の物理,研究会報告)
黒木 和彦; 臼井 秀知
物性研究刊行会, 2011, 物性研究, 96, 5, 536-536, Japanese, 0525-2997, 110008712468, AN0021948X

銅酸化物における超伝導転移温度の一軸性圧力効果の第一原理計算による解析
榊原寛史; 臼井秀知; 黒木和彦; 有田亮太郎; 有田亮太郎; 有田亮太郎; 青木秀夫; 青木秀夫
2011, 日本物理学会講演概要集, 66, 2, 1342-8349, 201102229778553683

23aWJ-8 Study on the large thermopower originating from high spin state in CaMnO_3
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 18 Aug. 2010, Meeting abstracts of the Physical Society of Japan, 65, 2, 456-456, Japanese, 1342-8349, 110008098172, AA11439205

26aWG-4 Lattice structure dependence of the d_ orbital mixing to the Fermi surface and its effect to the superconductivity in high T_c cuprate
Sakakibara H.; Usui H.; Kuroki K.; Arita R.; Aoki H.
The Physical Society of Japan (JPS), 18 Aug. 2010, Meeting abstracts of the Physical Society of Japan, 65, 2, 612-612, Japanese, 1342-8349, 110008098766, AA11439205

25pWH-7 Material and crystal structure dependence of the superconducting gap in 122 iron pnictide
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 18 Aug. 2010, Meeting abstracts of the Physical Society of Japan, 65, 2, 600-600, Japanese, 1342-8349, 110008098719, AA11439205

23pGA-2 Hybridization effect of d_ and d_ orbitals on the superconductivity in Lanthanum cuprates
Sakakibara H.; Usui H.; Kuroki K.; Arita R.; Aoki H.
The Physical Society of Japan (JPS), 01 Mar. 2010, Meeting abstracts of the Physical Society of Japan, 65, 1, 677-677, Japanese, 1342-8349, 110007656296, AA11439205

22pGD-10 Study on the origin of thermopower in K_xRhO_2 based on ab-initio calculation
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 01 Mar. 2010, Meeting abstracts of the Physical Society of Japan, 65, 1, 650-650, Japanese, 1342-8349, 110007656191, AA11439205

21pGH-2 3 dimensional 5 orbital effective model of 122 iron pnictide superconductors and its RPA analysis
Suzuki K.; Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 01 Mar. 2010, Meeting abstracts of the Physical Society of Japan, 65, 1, 633-633, Japanese, 1342-8349, 110007656146, AA11439205

La系銅酸化物におけるd_X軌道とd_Y軌道混成の超伝導に対する効果(X=x²-y²,Y=x²)
榊原寛史; 臼井秀知; 黒木和彦; 有田亮太郎; 有田亮太郎; 有田亮太郎; 青木秀夫; 青木秀夫
2010, 日本物理学会講演概要集, 65, 1, 1342-8349, 201002266802620147

銅酸化物超伝導におけるフェルミ面へのd_A(A=z²)軌道混成の効果と結晶構造の関係
榊原寛史; 榊原寛史; 臼井秀知; 黒木和彦; 黒木和彦; 有田亮太郎; 有田亮太郎; 有田亮太郎; 有田亮太郎; 青木秀夫; 青木秀夫
2010, 日本物理学会講演概要集, 65, 2, 1342-8349, 201002299934864270

26aRG-12 Study on the origin of thermopower in LaCoO_3 based on ab-initio downfolding
Usui H.; Kuroki K.
The Physical Society of Japan (JPS), 18 Aug. 2009, Meeting abstracts of the Physical Society of Japan, 64, 2, 468-468, Japanese, 1342-8349, 110007497690, AA11439205

26aPS-12 Hybridization effect of d_ and d_ orbitals in Lanthanum copper oxides
Sakakibara H.; Usui H.; Kuroki K.; Arita R.; Aoki H.
The Physical Society of Japan (JPS), 18 Aug. 2009, Meeting abstracts of the Physical Society of Japan, 64, 2, 480-480, Japanese, 1342-8349, 110007497740, AA11439205

30pTL-5 Study on the origin of large thermopower in oxides with perovskite structure based on ab-initio downfolding
Usui H.; Shibata S.; Kuroki K.
The Physical Society of Japan (JPS), 03 Mar. 2009, Meeting abstracts of the Physical Society of Japan, 64, 1, 667-667, Japanese, 1342-8349, 110007372164, AA11439205

La系銅酸化物におけるd_A:A=x²-y²軌道とd_B:B=x²軌道の混成効果
榊原寛史; 臼井秀知; 黒木和彦; 有田亮太郎; 青木秀夫
2009, 日本物理学会講演概要集, 64, 2, 1342-8349, 200902255193409180

鉄系超伝導体におけるニクトゲンの高さとペアリング対称性の相関
黒木和彦; 黒木和彦; 臼井秀知; 大成誠一郎; 大成誠一郎; 有田亮太郎; 有田亮太郎; 有田亮太郎; 青木秀夫; 青木秀夫
2009, 日本物理学会講演概要集, 64, 2, 1342-8349, 200902289695778530

Pudding mold type band as an origin for large thermopower in cobaltates and rhodates
黒木 和彦; 有田 亮太郎; 臼井 秀知
アグネ技術センタ-, Sep. 2008, Solid state physics, 43, 9, 569-579, Japanese, 0454-4544, 40016253494, AN00092629

20aYE-10 Core- and Valence-level Spectra of La(O_<1-x>F_x) FeAs Superconductor
Malaeb W.; Yoshida T.; Kataoka T.; Fujimori A.; Kubota M.; Ono K.; Usui H.; Kuroki K.; Arita R.; Aoki H.; Kamihara Y.; Hirano M.; Hosono H.
The Physical Society of Japan (JPS), 25 Aug. 2008, Meeting abstracts of the Physical Society of Japan, 63, 2, 690-690, English, 1342-8349, 110006985057, AA11439205

第一原理計算に基づくLaRhO₃の高い熱起電力の研究:最局在ワニエ基底による解析
臼井秀知; 黒木和彦; 有田亮太郎
2008, 日本物理学会講演概要集, 63, 2, 1342-8349, 200902231210296364

鉄砒素系超伝導体の有効模型とペアリング・メカニズム
黒木和彦; 大成誠一郎; 有田亮太郎; 臼井秀知; 田仲由喜夫; 紺谷浩; 青木秀夫
2008, 日本物理学会講演概要集, 63, 2, 1342-8349, 200902206254429375

Electronic Structure and Electron Correlation in LaFeAsO1-xFx and LaFePO1-xFx
Malaeb Walid; Yoshida Teppei; Kataoka Takashi; Fujimori Atsushi; Kubota Masato; Ono Kanta; Usui Hidetomo; Kuroki Kazuhiko; Arita Ryotaro; Aoki Hideo; Kamihara Yoichi; Hirano Masahiro; Hosono Hideo
Photoemission spectroscopy is used to investigate the electronic structure of the newly discovered iron-based superconductors LaFeAsO1-xFx and LaFePO1-xFx. Line shapes of the Fe $2 p$ core-level spectra suggest an itinerant character of Fe $3d$ electrons. The valence-band spectra are generally consistent with band-structure calculations except for the shifts of Fe $3d$-derived peaks toward the Fermi level. From the spectra taken in the Fe $3 p$ $\to$ $3d$ core-absorption region, we have obtained the experimental Fe $3d$ partial density of states, and explained it in terms of a band-structure calculation with a phenomenological self-energy correction, yielding a mass renormalization factor of ${\lesssim}2$., The Physical Society of Japan (JPS), 2008, J Phys Soc Jpn, 77, 9, 093714-093714-4, English, 0031-9015, 110006933475, AA00704814, 60777862

21aPS-7 "Flower-shaped" Fermi surface due to incommensurate SDW in Na_xCoO_2
Usui Hidetomo; Kuroki Kazuhiko
The Physical Society of Japan (JPS), 21 Aug. 2007, Meeting abstracts of the Physical Society of Japan, 62, 2, 520-520, Japanese, 1342-8349, 110007141144, AA11439205

第一原理計算による高エントロピー高性能熱電材料の設計指針構築
臼井 秀知
日本学術振興会, 科学研究費助成事業, 島根大学, 基盤研究(C), 24K08231
01 Apr. 2024 - 31 Mar. 2027

Development of materials with axis-dependent conduction polarity for transverse thermoelectric module
後藤 陽介; 臼井 秀知
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, National Institute of Advanced Industrial Science and Technology, Grant-in-Aid for Challenging Research (Pioneering), 23K17342
30 Jun. 2023 - 31 Mar. 2027

Theoretical sutdy on high-mobility thermoelectric materials using topology
Usui Hidetomo
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Shimane University, Grant-in-Aid for Early-Career Scientists, The thermoelectric effect refers to the phenomenon of conversion from heat to electricity or from electricity to heat. Because of its characteristics, it is attracting attention as a possible solution to energy problems through power generation using waste heat. However, there are not many materials with high performance, and theoretical design guidelines are needed. In this study, we theoretically studied a compound with a triangular lattice structure having high mobility due to its topological origin. As a result, theoretical analyses were performed for 25 1-2-2 Zintl-phase compounds, and we found a factor for obtaining high thermoelectric performance materials and found some high-performance thermoelectric materials. We studied the origin of thermoelectric performance for various materials exhibiting axis-dependent conduction polarity., 19K15436
01 Apr. 2019 - 31 Mar. 2022

Band-shape engineering of thermoelectric materials for high thermoelectric efficiency
Usui Hidetomo
Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Osaka University, Grant-in-Aid for Young Scientists (B), The thermoelectric effect is a direct conversion of heat to electricity or vice versa. In this study, we instigated new thermoelectric materials by means of band-shape engineering, which means that shape of electronic band structures is modified by substituting constituent elements of compounds in order to enhance thermoelectric efficiency. We found that LaOAsSe2, in which As and Se are hypothetically substituted with Bi and S of LaOBiS2, can exhibit large thermoelectric performance with the dimensionless figure of merit ZT > 2., 17K14108
01 Apr. 2017 - 31 Mar. 2019

第一原理バンド計算からの有効模型構築に基づく異常量子輸送現象の理論的研究
臼井 秀知
日本学術振興会, 科学研究費助成事業, 電気通信大学, 特別研究員奨励費, エネルギー問題を解決への貢献も視野に入れて、【超伝導】と【熱電効果】について理論研究を行った。研究目的として【超伝導】1.鉄系超伝導体に対し、超伝導発現機構を探ることで超伝導のさらなる理解を目指す。2.旧来の閤題である銅酸化物高温超伝導体の臨界温度の差異を探求した。これらの研究の全てをコンピュータによる数値計算を用いて行い、本研究では第一原理計算から得られたバンド構造を用いて理論解析を行うアプローチをとっている。【熱電効果】金属的伝導性と大きなゼーベック係数を持ち合わせた熱電物質を作成するために、どのような指針を持つことが必要か研究を行った。研究内容として、酸化物熱電物質の代表例であるNa_xCoO_2の対し、スピン揺らぎの熱電効果に対する影響を調べた。その結果、界ピン揺らぎ効果によってバンド構造が大きく変化し、このバンド構造の変化はゼーベック効果に対して有利に働くことがわかった。【超伝導】1.鉄系超伝導体の超伝導転移温度の起源と差異を乱雑位相近似、揺らぎ交換近似を用いて調べた。(1)超伝導転移温度について鉄ヒ素結合角を横軸にとった場合、正四面体近くで最大値を取ることが実験でわかっていたが、それを理論的に確かめ、さらなる転移温度を目指す指針を与えることができた。(2)3次元的な軌道混成を持つバンド構造がフェルミ面に存在する場合、超伝導ギャップ関数がゼロとなるノードのある超伝導が存在する可能性を示した。(3)21311系と呼ばれる物質について、仮想的に結晶構造を変化させた場合、鉄系超伝導体では特有な超伝導ギャップ関数が得られることがわかった。2. 1層系銅酸化物高温超伝導体の転移温度の差異がd_軌道とd_軌道のエネルギー差から説明でき、その起源は2つのパラメータから理解可能であることがわかった。また、この理論から実験で観測されている圧力による超伝導転移温度の変化を定性的に説明することができた。, 09J08306
2009 - 2011