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Ryu Yukawa

Section

International Center for Synchrotron Radiation Innovation Smart

Job title

Associate Professor

Degree

博士（理学）（東京大学）
修士（理学）（東京大学）

researchmap

https://researchmap.jp/Ryu_Yukawa

J-GLOBAL ID

201701006564904596

e-Rad No.

40759479

ORCID

https://orcid.org/0000-0002-5066-9445

Research History 4

2023/06 - Present

Tohoku University　International Center for Synchrotron Radiation Innovation Smart　Associate professor
2019/11 - 2023/05

Osaka University　Graduate School of Engineering
2017/09 - 2019/10

High Energy Accelerator Research Organization (KEK)　Institute of Materials Structure Science　Research Assistant Professor
2015/04 - 2017/08

High Energy Accelerator Research Organization (KEK)　Institute of Materials Structure Science　Postdoctoral fellow

Education 2

The University of Tokyo　Graduate School of Science　Department of Physics

2010/04 - 2015/03
Tokyo University of Science　Faculty of Science Division I　Department of Physics

2004/04 - 2010/03

Committee Memberships 6

The Japan Society of Vacuum and Surface Science　Public Relations Officers of e-Journal of Surface Science and Nanotechnology

2022/04 - Present
11th Annual Ambient Pressure X-ray Photoelectron Spectroscopy Workshop (APXPS 2024)　Local Organizing Committee

2023/08 - 2024/12
International Vacuum Congress (IVC-22)　Program Subcommittees

2021/12 - 2022/09
2021年日本表面真空学会学術講演会　プログラム委員

2021/09 - 2021/11
Physical Society of Japan　領域９運営委員

2020/10 - 2021/03
日本表面真空学会　電子ジャーナル制作小委員会

2020/04 - 2021/03

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Professional Memberships 3

The Japan Society of Vacuum and Surface Science
The Japanese Society for Synchrotron Radiation Research
Physical Society of Japan

Research Interests 5

Transition metal oxide
Angle-Resolved Photoemission Spectroscopy
Photoemission Spectroscopy
Solid State Physics
Synchrotron Radiation

Research Areas 3

Nanotechnology/Materials / Thin-film surfaces and interfaces /
Energy / Quantum beam science /
Natural sciences / Semiconductors, optical and atomic physics /

Awards 2

論文賞

2022/03　応用物理学会薄膜・表面物理分科会
The 17th Hiroshima International Symposium on Synchrotron Radiation

2013/02　Best Student Poster Award

Papers 65

Probe-position determination with multichannel I - V measurements in a two-dimensional sheet : Computational method and mathematical analysis Peer-reviewed

Tomoyuki Iori, Ryu Yukawa

Physical Review Applied　23　(3)　034064　2025/03/25
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevapplied.23.034064 　

eISSN： 2331-7019
Two-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2

Takuto Nakamura, Hiroki Sugihara, Yitong Chen, Ryu Yukawa, Yoshiyuki Ohtsubo, Kiyohisa Tanaka, Miho Kitamura, Hiroshi Kumigashira, Shin-ichi Kimura

Nature Communications　14　(1)　2023/12/01
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41467-023-43662-9 　

eISSN： 2041-1723

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Abstract The Kondo effect between localized f-electrons and conductive carriers leads to exotic physical phenomena. Among them, heavy-fermion (HF) systems, in which massive effective carriers appear due to the Kondo effect, have fascinated many researchers. Dimensionality is also an important characteristic of the HF system, especially because it is strongly related to quantum criticality. However, the realization of the perfect two-dimensional (2D) HF materials is still a challenging topic. Here, we report the surface electronic structure of the monoatomic-layer Kondo lattice YbCu₂ on a Cu(111) surface observed by synchrotron-based angle-resolved photoemission spectroscopy. The 2D conducting band and the Yb 4f state, located very close to the Fermi level, are observed. These bands are hybridized at low-temperature, forming the 2D HF state, with an evaluated coherence temperature of about 30 K. The effective mass of the 2D state is enhanced by a factor of 100 by the development of the HF state. Furthermore, clear evidence of the hybridization gap formation in the temperature dependence of the Kondo-resonance peak has been observed below the coherence temperature. Our study provides a new candidate as an ideal 2D HF material for understanding the Kondo effect at low dimensions.
Surface valence transition in SmS by alkali metal adsorption

Takuto Nakamura, Toru Nakaya, Yoshiyuki Ohtsubo, Hiroki Sugihara, Kiyohisa Tanaka, Ryu Yukawa, Miho Kitamura, Hiroshi Kumigashira, Keiichiro Imura, Hiroyuki S. Suzuki, Noriaki K. Sato, Shin-ichi Kimura

Physical Review B　107　(4)　2023/01/05
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevb.107.l041102 　

ISSN： 2469-9950

eISSN： 2469-9969
Resolving decay-time dependent photoluminescence induced by phonon-dressed excitons in ZnO Peer-reviewed

Ryu Yukawa, Susumu Yamamoto, Ren Arita, Yuki Minami, Kohei Yamanoi, Kenichi Ozawa, Kazuyuki Sakamoto, Toshihiko Shimizu, Nobuhiko Sarukura, Iwao Matsuda

Physical Review Materials　6　(10)　2022/10/21
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevmaterials.6.104607 　

eISSN： 2475-9953
Resonant tunneling driven metal-insulator transition in double quantum-well structures of strongly correlated oxide Peer-reviewed

R. Yukawa, M. Kobayashi, T. Kanda, D. Shiga, K. Yoshimatsu, S. Ishibashi, M. Minohara, M. Kitamura, K. Horiba, A. F. Santander-Syro, H. Kumigashira

Nature Communications　12　(1)　2021/12

DOI： 10.1038/s41467-021-27327-z 　

eISSN： 2041-1723
Electronic structure of SrTi1−xVxO3 films studied by in situ photoemission spectroscopy: Screening for a transparent electrode material Peer-reviewed

Tatsuhiko Kanda, Daisuke Shiga, Ryu Yukawa, Naoto Hasegawa, Duy Khanh Nguyen, Xianglin Cheng, Ryosuke Tokunaga, Miho Kitamura, Koji Horiba, Kohei Yoshimatsu, Hiroshi Kumigashira

Physical Review B　104　(11)　2021/09/10
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevb.104.115121 　

ISSN： 2469-9950

eISSN： 2469-9969
Hard and soft x-ray photoemission spectroscopy study of the new Kondo system SmO thin film Peer-reviewed

Shoya Sakamoto, Kenichi Kaminaga, Daichi Oka, Ryu Yukawa, Masafumi Horio, Yuichi Yokoyama, Kohei Yamamoto, Kou Takubo, Yosuke Nonaka, Keisuke Koshiishi, Masaki Kobayashi, Arata Tanaka, Akira Yasui, Eiji Ikenaga, Hiroki Wadati, Hiroshi Kumigashira, Tomoteru Fukumura, Atsushi Fujimori

Physical Review Materials　4　(9)　2020/09/18

DOI： 10.1103/physrevmaterials.4.095001 　

ISSN： 2475-9953

eISSN： 2475-9953
Thickness dependence of electronic structures in VO2 ultrathin films: Suppression of the cooperative Mott-Peierls transition Peer-reviewed

D. Shiga, B. E. Yang, N. Hasegawa, T. Kanda, R. Tokunaga, K. Yoshimatsu, R. Yukawa, M. Kitamura, K. Horiba, H. Kumigashira

Physical Review B　102　(11)　2020/09/09
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevb.102.115114 　

ISSN： 2469-9950

eISSN： 2469-9969
Molecular beam epitaxy growth of the highly conductive oxide SrMoO3 Peer-reviewed

Hiroshi Takatsu, Naoya Yamashina, Daisuke Shiga, Ryu Yukawa, Koji Horiba, Hiroshi Kumigashira, Takahito Terashima, Hiroshi Kageyama

Journal of Crystal Growth　543　125685-125685　2020/08
Publisher: Elsevier BV
DOI： 10.1016/j.jcrysgro.2020.125685 　

ISSN： 0022-0248
Electronic structure of a (3×3)-ordered silicon layer on Al(111) Peer-reviewed

Yusuke Sato, Yuki Fukaya, Mathis Cameau, Asish K. Kundu, Daisuke Shiga, Ryu Yukawa, Koji Horiba, Chin-Hsuan Chen, Angus Huang, Horng-Tay Jeng, Taisuke Ozaki, Hiroshi Kumigashira, Masahito Niibe, Iwao Matsuda

Physical Review Materials　4　(6)　2020/06/15
Publisher: American Physical Society (APS)
DOI： 10.1103/physrevmaterials.4.064005 　

eISSN： 2475-9953
Tunable two-dimensional electron system at the (110) surface of SnO2 Peer-reviewed

J. Dai, E. Frantzeskakis, F. Fortuna, P. Lömker, R. Yukawa, M. Thees, S. Sengupta, P. Le Fèvre, F. Bertran, J. E. Rault, K. Horiba, M. Müller, H. Kumigashira, A. F. Santander-Syro

Physical Review B　101　(8)　2020/02/15

DOI： 10.1103/PhysRevB.101.085121 　

ISSN： 2469-9950

eISSN： 2469-9969
Two-dimensional conducting layer on SrTiO3 surface induced by hydrogenation Peer-reviewed

Y. Takeuchi, R. Hobara, R. Akiyama, A. Takayama, S. Ichinokura, R. Yukawa, I. Matsuda, S. Hasegawa

Phys. Rev. B　101　085422　2020/02
Evolution of Electronic States and Emergence of Superconductivity in the Polar Semiconductor GeTe by Doping Valence-Skipping Indium Peer-reviewed

M. Kriener, M. Sakano, M. Kamitani, M. S. Bahramy, R. Yukawa, K. Horiba, H. Kumigashira, K. Ishizaka, Y. Tokura, Y. Taguchi

Physical Review Letters　124　(4)　2020/01/31

DOI： 10.1103/PhysRevLett.124.047002 　

ISSN： 0031-9007

eISSN： 1079-7114
Surface Proton Conduction of Sm-Doped CeO<inf>2-δ</inf> Thin Film Preferentially Grown on Al<inf>2</inf>O<inf>3</inf> (0001) Peer-reviewed

D. Nishioka, T. Tsuchiya, W. Namiki, M. Takayanagi, K. Kawamura, T. Fujita, R. Yukawa, K. Horiba, H. Kumigashira, T. Higuchi

Nanoscale Research Letters　15　(1)　2020

DOI： 10.1186/s11671-020-3267-5 　

ISSN： 1931-7573

eISSN： 1556-276X
Relationship between charge redistribution and ferromagnetism at the heterointerface between the perovskite oxides LaNi O3 and LaMn O3 Peer-reviewed

Miho Kitamura, Masaki Kobayashi, Enju Sakai, Makoto Minohara, Ryu Yukawa, Daisuke Shiga, Kenta Amemiya, Yosuke Nonaka, Goro Shibata, Atsushi Fujimori, Hiroshi Fujioka, Koji Horiba, Hiroshi Kumigashira

Physical Review B　10　(24)　245132　2019/12/19

DOI： 10.1103/PhysRevB.100.245132 　

ISSN： 2469-9950

eISSN： 2469-9969
Non-trivial surface states of samarium hexaboride at the (111) surface Peer-reviewed

Yoshiyuki Ohtsubo, Yuki Yamashita, Kenta Hagiwara, Shin-ichiro Ideta, Kiyohisa Tanaka, Ryu Yukawa, Koji Horiba, Hiroshi Kumigashira, Koji Miyamoto, Taichi Okuda, Wataru Hirano, Fumitoshi Iga, Shin-ichi Kimura

Nature Communications　10　(1)　2298　2019/12

DOI： 10.1038/s41467-019-10353-3 　

ISSN： 2041-1723

eISSN： 2041-1723
Natural van der Waals heterostructural single crystals with both magnetic and topological properties. Peer-reviewed

Wu J, Liu F, Sasase M, Ienaga K, Obata Y, Yukawa R, Horiba K, Kumigashira H, Okuma S, Inoshita T, Hosono H

Science advances　5　(11)　eaax9989　2019/11

DOI： 10.1126/sciadv.aax9989 　
Surface Electron-Ion Mixed Conduction of Ti0.99Sc0.01O2-delta Thin Film with Lattice Distortion and Oxygen Vacancies Peer-reviewed

Kawamura Kinya, Sekine Masaki, Nishioka Daiki, Yukawa Ryu, Horiba Koji, Kumigashira Hiroshi, Higuchi Tohru

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　88　(5)　2019/05/15

DOI： 10.7566/JPSJ.88.054711 　

ISSN： 0031-9015
Electronic structure of a monoatomic Cu2Si layer on a Si(111) substrate Peer-reviewed

Cameau M, Yukawa R, Chen C-H, Huang A, Ito S, Ishibiki R, Horiba K, Obata Y, Kondo T, Kumigashira H, Jeng H-T, D'angelo M, Matsuda I

PHYSICAL REVIEW MATERIALS　3　(4)　2019/04/24

DOI： 10.1103/PhysRevMaterials.3.044004 　

ISSN： 2475-9953

eISSN： 2475-9953
Emergence of metallic monoclinic states of VO2 films induced by K deposition Peer-reviewed

Shiga, D., Minohara, M., Kitamura, M., Yukawa, R., Horiba, K., Kumigashira, H.

Physical Review B　99　(12)　2019

DOI： 10.1103/PhysRevB.99.125120 　

ISSN： 2469-9950
Growth of antiperovskite oxide Ca3SnO films by pulsed laser deposition Peer-reviewed

Makoto Minohara, Ryu Yukawa, Miho Kitamura, Reiji Kumai, Youichi Murakami, Hiroshi Kumigashira

Journal of Crystal Growth　500　33-37　2018/10
Publisher: Elsevier {BV}
DOI： 10.1016/j.jcrysgro.2018.08.014 　

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We report the epitaxial growth of Ca3SnO antiperovskite oxide films on (001)-oriented cubic yttria-stabilized zirconia (YSZ) substrates by using a conventional pulsed laser deposition (PLD) technique. In this work, a sintered Ca3SnO pellet is used as the ablation target. X-ray diffraction measurements demonstrate the (001) growth of Ca3SnO films with the antiperovskite structure and a cube-on-cube orientation relationship to the YSZ substrate. The successful synthesis of the antiperovskite phase is further confirmed by x-ray photoemission spectroscopy. These results strongly suggest that antiperovskite-oxide films can be directly grown on substrates from the target material using a PLD technique.
Giant Rashba splitting of quasi-one-dimensional surface states on Bi/InAs(110)-(2 x 1) Peer-reviewed

Nakamura Takuto, Ohtsubo Yoshiyuki, Yamashita Yuki, Ideta Shin-ichiro, Tanaka Kiyohisa, Yaji Koichiro, Harasawa Ayumi, Shin Shik, Komori Fumio, Yukawa Ryu, Horiba Koji, Kumigashira Hiroshi, Kimura Shin-ichi

PHYSICAL REVIEW B　98　(7)　2018/08/27

DOI： 10.1103/PhysRevB.98.075431 　

ISSN： 2469-9950

eISSN： 2469-9969
Element Selectivity in Second-Harmonic Generation of GaFeO3 by a Soft-X-Ray Free-Electron Laser Peer-reviewed

Sh. Yamamoto, T. Omi, H. Akai, Y. Kubota, Y. Takahashi, Y. Suzuki, Y. Hirata, K. Yamamoto, R. Yukawa, K. Horiba, H. Yumoto, T. Koyama, H. Ohashi, S. Owada, K. Tono, M. Yabashi, E. Shigemasa, S. Yamamoto, M. Kotsugi, H. Wadati, H. Kumigashira, T. Arima, S. Shin, I. Matsuda

Physical Review Letters　120　(22)　2018/06/01

DOI： 10.1103/PhysRevLett.120.223902 　

ISSN： 1079-7114 0031-9007

eISSN： 1079-7114
High-density two-dimensional electron system induced by oxygen vacancies in ZnO Peer-reviewed

T. C. Rödel, J. Dai, F. Fortuna, E. Frantzeskakis, P. Le Fèvre, F. Bertran, M. Kobayashi, R. Yukawa, T. Mitsuhashi, M. Kitamura, K. Horiba, H. Kumigashira, A. F. Santander-Syro

Physical Review Materials　2　(5)　2018/05/14

DOI： 10.1103/PhysRevMaterials.2.051601 　

ISSN： 2475-9953

eISSN： 2475-9953
Correlation between Photocatalytic Activity and Carrier Lifetime: Acetic Acid on Single-Crystal Surfaces of Anatase and Rutile TiO2 Peer-reviewed

Kenichi Ozawa, Susumu Yamamoto, Ryu Yukawa, Ro-Ya Liu, Naoya Terashima, Yuto Natsui, Hiroo Kato, Kazuhiko Mase, Iwao Matsuda

Journal of Physical Chemistry C　122　(17)　9562-9569　2018/05/03

DOI： 10.1021/acs.jpcc.8b02259 　

ISSN： 1932-7455 1932-7447

eISSN： 1932-7455
Surface electronic structure of SmB6(111) Peer-reviewed

Yoshiyuki Ohtsubo, Kenta Hagiwara, Chengwei Wang, Ryu Yukawa, Koji Horiba, Hiroshi Kumigashira, Wataru Hirano, Fumitoshi Iga, Shin-ichi Kimura

Physica B: Condensed Matter　536　75-77　2018/05/01

DOI： 10.1016/j.physb.2017.09.033 　

ISSN： 0921-4526
Converting topological insulators into topological metals within the tetradymite family Peer-reviewed

K. W. Chen, N. Aryal, J. Dai, D. Graf, S. Zhang, S. Das, P. Le Fèvre, F. Bertran, R. Yukawa, K. Horiba, H. Kumigashira, E. Frantzeskakis, F. Fortuna, L. Balicas, A. F. Santander-Syro, E. Manousakis, R. E. Baumbach

Physical Review B　97　(16)　2018/04/09

DOI： 10.1103/PhysRevB.97.165112 　

ISSN： 2469-9969 2469-9950
Peculiar bonding associated with atomic doping and hidden honeycombs in borophene Peer-reviewed

Chi-Cheng Lee, Baojie Feng, Marie D'Angelo, Ryu Yukawa, Ro-Ya Liu, Takahiro Kondo, Hiroshi Kumigashira, Iwao Matsuda, Taisuke Ozaki

Physical Review B　97　(7)　2018/02/20
Publisher: American Physical Society
DOI： 10.1103/PhysRevB.97.075430 　

ISSN： 2469-9969 2469-9950

eISSN： 2469-9969
Single-layer dual germanene phases on Ag(111) Peer-reviewed

Lin Chung-Huang, Huang Angus, Pai Woei Wu, Chen Wei-Chuan, Chen Ting-Yu, Chang Tay-Rong, Yukawa Ryu, Cheng Cheng-Maw, Mou Chung-Yu, Matsuda Iwao, Chiang T. -C, Jeng H. -T, Tang S. -J

PHYSICAL REVIEW MATERIALS　2　(2)　2018/02/09

DOI： 10.1103/PhysRevMaterials.2.024003 　

ISSN： 2475-9953
Surface electronic states of Au-induced nanowires on Ge(0 0 1) Peer-reviewed

Koichiro Yaji, Ryu Yukawa, Sunghun Kim, Yoshiyuki Ohtsubo, Patrick Le Fèvre, François Bertran, Amina Taleb-Ibrahimi, Iwao Matsuda, Kan Nakatsuji, Shik Shin, Fumio Komori

Journal of Physics Condensed Matter　30　(7)　2018/01/19

DOI： 10.1088/1361-648X/aaa526 　

ISSN： 1361-648X 0953-8984

eISSN： 1361-648X
Control of two-dimensional electronic states at anatase TiO2 (001) surface by K adsorption Peer-reviewed

Yukawa, R., Minohara, M., Shiga, D., Kitamura, M., Mitsuhashi, T., Kobayashi, M., Horiba, K., Kumigashira, H.

Physical Review B　97　(16)　2018

DOI： 10.1103/PhysRevB.97.165428 　

ISSN： 2469-9950
ARPES studies of the inverse perovskite Ca3PbO: Experimental confirmation of a candidate 3D Dirac fermion system Peer-reviewed

Yukiko Obata, Ryu Yukawa, Koji Horiba, Hiroshi Kumigashira, Yoshitake Toda, Satoru Matsuishi, Hideo Hosono

PHYSICAL REVIEW B　96　(15)　2017/10

DOI： 10.1103/PhysRevB.96.155109 　

ISSN： 2469-9950

eISSN： 2469-9969
Semimetallic bands derived from interlayer electrons in the quasi-two-dimensional electride Y2C Peer-reviewed

Koji Horiba, Ryu Yukawa, Taichi Mitsuhashi, Miho Kitamura, Takeshi Inoshita, Noriaki Hamada, Shigeki Otani, Naoki Ohashi, Sachiko Maki, Jun-ichi Yamaura, Hideo Hosono, Youichi Murakami, Hiroshi Kumigashira

PHYSICAL REVIEW B　96　(4)　2017/07

DOI： 10.1103/PhysRevB.96.045101 　

ISSN： 2469-9950

eISSN： 2469-9969
Surface state of the dual topological insulator Bi(0.9)1Sb(0.09)(11(2)over-bar) Peer-reviewed

I. Matsuda, K. Yaji, A. A. Taskin, M. D'angelo, R. Yukawa, Y. Ohtsubo, P. Le Fevre, F. Bertran, S. Yoshizawa, A. Taleb-Ibrahimi, A. Kakizaki, Yoichi Ando, F. Komori

PHYSICA B-CONDENSED MATTER　516　100-104　2017/07

DOI： 10.1016/j.physb.2017.04.031 　

ISSN： 0921-4526

eISSN： 1873-2135
Highly hydrogen-sensitive thermal desorption spectroscopy system for quantitative analysis of low hydrogen concentration (∼1 × 1016 atoms/cm3) in thin-film samples

Taku Hanna, Hidenori Hiramatsu, Isao Sakaguchi, Hideo Hosono

Review of Scientific Instruments　88　(5)　053103-053103　2017/05
Publisher: {AIP} Publishing
DOI： 10.1063/1.4982255 　

ISSN： 0034-6748 1089-7623
Temperature dependence of Yb valence in the sub-surface of YbB12(001) Peer-reviewed

Kenta Hagiwara, Yusuke Takeno, Yoshiyuki Ohtsubo, Ryu Yukawa, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, Julien Rault, Patrick Le Fevre, Francois Bertran, Amina Taleb-Ibrahimi, Fumitoshi Iga, Shin-Ichi Kimura

Journal of Physics: Conference Series　807　(1)　012003　2017/04/06

DOI： 10.1088/1742-6596/807/1/012003 　

ISSN： 1742-6596 1742-6588
Dirac Fermions in Borophene Peer-reviewed

Baojie Feng, Osamu Sugino, Ro-Ya Liu, Jin Zhang, Ryu Yukawa, Mitsuaki Kawamura, Takushi Iimori, Howon Kim, Yukio Hasegawa, Hui Li, Lan Chen, Kehui Wu, Hiroshi Kumigashira, Fumio Komori, Tai-Chang Chiang, Sheng Meng, Iwao Matsuda

PHYSICAL REVIEW LETTERS　118　(9)　2017/03

DOI： 10.1103/PhysRevLett.118.096401 　

ISSN： 0031-9007

eISSN： 1079-7114
Time-resolved soft X-ray core-level photoemission spectroscopy at 880 degrees C using the pulsed laser and synchrotron radiation and the pulse heating current Peer-reviewed

T. Abukawa, S. Yamamoto, R. Yukawa, S. Kanzaki, K. Mukojima, I. Matsuda

SURFACE SCIENCE　656　43-47　2017/02

DOI： 10.1016/j.susc.2016.09.006 　

ISSN： 0039-6028

eISSN： 1879-2758
Emergence of Quantum Critical Behavior in Metallic Quantum-Well States of Strongly Correlated Oxides Peer-reviewed

Kobayashi, Masaki, Yoshimatsu, Kohei, Mitsuhashi, Taichi, Kitamura, Miho, Sakai, Enju, Yukawa, Ryu, Minohara, Makoto, Fujimori, Atsushi, Horiba, Koji, Kumigashira, Hiroshi

Scientific Reports　7　2017

DOI： 10.1038/s41598-017-16666-x 　

ISSN： 2045-2322
Hubbard band versus oxygen vacancy states in the correlated electron metal SrVO3 Peer-reviewed

S. Backes, T. C. Rodel, F. Fortuna, E. Frantzeskakis, P. Le Fevre, F. Bertran, M. Kobayashi, R. Yukawa, T. Mitsuhashi, M. Kitamura, K. Horiba, H. Kumigashira, R. Saint-Martin, A. Fouchet, B. Berini, Y. Dumont, A. J. Kim, F. Lechermann, H. O. Jeschke, M. J. Rozenberg, R. Valenti, A. F. Santander-Syro

PHYSICAL REVIEW B　94　(24)　2016/12

DOI： 10.1103/PhysRevB.94.241110 　

ISSN： 2469-9950

eISSN： 2469-9969
What Determines the Lifetime of Photoexcited Carriers on TiO2 Surfaces? Peer-reviewed

Kenichi Ozawa, Susumu Yamamoto, Ryu Yukawa, Roya Liu, Masato Emori, Koki Inoue, Taku Higuchi, Hiroshi Sakama, Kazuhiko Mase, Iwao Matsuda

JOURNAL OF PHYSICAL CHEMISTRY C　120　(51)　29283-29289　2016/12

DOI： 10.1021/acs.jpcc.6b10136 　

ISSN： 1932-7447

eISSN： 1932-7455
Tailoring Photovoltage Response at SrRuO3/SrTiO3 Heterostructures Peer-reviewed

Ryu Yukawa, Susumu Yamamoto, Kazuma Akikubo, Kaori Takeuchi, Kenichi Ozawa, Hiroshi Kumigashira, Iwao Matsuda

ADVANCED MATERIALS INTERFACES　3　(22)　2016/11

DOI： 10.1002/admi.201600527 　

ISSN： 2196-7350
Phonon-dressed two-dimensional carriers on the ZnO surface Peer-reviewed

R. Yukawa, K. Ozawa, S. Yamamoto, H. Iwasawa, K. Shimada, E. F. Schwier, K. Yoshimatsu, H. Kumigashira, H. Namatame, M. Taniguchi, I. Matsuda

PHYSICAL REVIEW B　94　(16)　2016/10

DOI： 10.1103/PhysRevB.94.165313 　

ISSN： 2469-9950

eISSN： 2469-9969
Investigation of Photo-carrier Generation Processes of Organic Solar Cells Using Time Resolved X-ray Photoelectron Spectroscopy Peer-reviewed

SAKURAI, TAKEAKI, Ozawa, Kenichi, Yukawa, Ryu, K.Akikubo, K.Takeuchi, S.Yamamoto, Matsuda, Iwao

Extended Abstracts of the 2016 International Conference on Solid State Devices and Materials (SSDM)　277-278　2016/09
Surface Kondo effect and non-trivial metallic state of the Kondo insulator YbB12 Peer-reviewed

Kenta Hagiwara, Yoshiyuki Ohtsubo, Masaharu Matsunami, Shin-ichiro Ideta, Kiyohisa Tanaka, Hidetoshi Miyazaki, Julien E. Rault, Patrick Le Fevre, Francois Bertran, Amina Taleb-Ibrahimi, Ryu Yukawa, Masaki Kobayashi, Koji Horiba, Hiroshi Kumigashira, Kazuki Sumida, Taichi Okuda, Fumitoshi Iga, Shin-ichi Kimura

NATURE COMMUNICATIONS　7　2016/08

DOI： 10.1038/ncomms12690 　

ISSN： 2041-1723
Capturing transiently charged states at the C-60/TiO2(110) interface by time-resolved soft X-ray photoelectron spectroscopy Peer-reviewed

Kenichi Ozawa, Susumu Yamamoto, Ryu Yukawa, Kazuma Akikubo, Masato Emori, Hiroshi Sakama, Iwao Matsuda

ORGANIC ELECTRONICS　31　98-103　2016/04

DOI： 10.1016/j.orgel.2016.01.020 　

ISSN： 1566-1199

eISSN： 1878-5530
Spin and Angle-Resolved Photoelectron Spectroscopy of (001) Surface State of The Kondo Insulator YbB₁₂

Hagiwara K., Ohtsubo Y., Takeno Y., Yukawa R., Kobayashi M., Horiba H., Kumigashira H., Sumida K., Okuda T., Iga F., Kimura S.

Meeting Abstracts of the Physical Society of Japan　71　1392-1392　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_1392 　
Influence of k(perpendicular to) broadening on ARPES spectra of the (110) and (001) surfaces of SrVO3 films Peer-reviewed

Mitsuhashi, T., Minohara, M., Yukawa, R., Kitamura, M., Horiba, K., Kobayashi, M., Kumigashira, H.

Physical Review B　94　(12)　2016

DOI： 10.1103/PhysRevB.94.125148 　

ISSN： 2469-9950
An Effective Approach to Improving Cadmium Telluride (111)A Surface by Molecular-Beam-Epitaxy Growth of Tellurium Monolayer Peer-reviewed

Jie Ren, Li Fu, Guang Bian, Jie Su, Hao Zhang, Saavanth Velury, Ryu Yukawa, Longxiang Zhang, Tao Wang, Gangqiang Zha, Rongrong Guo, Tom Miller, M. Zahid Hasan, Tai-Chang Chiang

ACS APPLIED MATERIALS & INTERFACES　8　(1)　726-735　2016/01

DOI： 10.1021/acsami.5609863 　

ISSN： 1944-8244
Anisotropic effective mass approximation model to calculate multiple subband structures at wide-gap semiconductor surfaces: Application to accumulation layers of SrTiO3 and ZnO Peer-reviewed

R. Yukawa, K. Ozawa, S. Yamamoto, R. -Y. Liu, I. Matsuda

SURFACE SCIENCE　641　224-230　2015/11

DOI： 10.1016/j.susc.2015.07.007 　

ISSN： 0039-6028

eISSN： 1879-2758
Photoemission Circular Dichroism and Spin Polarization of the Topological Surface States in Ultrathin Bi2Te3 Films Peer-reviewed

C. -Z. Xu, Y. Liu, R. Yukawa, L. -X. Zhang, I. Matsuda, T. Miller, T. -C. Chiang

PHYSICAL REVIEW LETTERS　115　(1)　2015/06

DOI： 10.1103/PhysRevLett.115.016801 　

ISSN： 0031-9007

eISSN： 1079-7114
Experimental evidence for two-dimensional states localized in subsurface region of Ge(111) Peer-reviewed

Koichiro Yaji, Yoshiyuki Ohtsubo, Shinichiro Hatta, Hiroshi Okuyama, Ryu Yukawa, Iwao Matsuda, Patrick Le Fevre, Francois Bertran, Amina Taleb-Ibrahimi, Akito Kakizaki, Tetsuya Aruga

JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA　201　92-97　2015/05

DOI： 10.1016/j.elspec.2014.09.005 　

ISSN： 0368-2048

eISSN： 1873-2526
Photoexcited carrier behaviour at the fullerene/titania interface studied by time-resolved photoelectron spectroscopy

Ozawa Kenichi, Emori Masato, Yukawa Ryu, Akikubo Kazuma, Sakama Hiroshi, Yamamoto Susumu, Matsuda Iwao

Abstract of annual meeting of the Surface Science of Japan　35　88　2015
Publisher: The Japan Society of Vacuum and Surface Science
DOI： 10.14886/sssj2008.35.0_88 　
24aAS-6 Two-dimensional surface states of Au-induced atomic nanowires on Ge(001)

Yaji K., Yukawa R., Kim S., Ohtsubo Y., Le Fevre Patrick, Bertran Francois, Taleb-Ibrahimi Amina, Matsuda I., Nakatsuji K., Komori F.

Meeting Abstracts of the Physical Society of Japan　70　2653-2653　2015
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.70.1.0_2653 　

ISSN： 2189-079X
Electron-hole recombination on ZnO(0001) single-crystal surface studied by time-resolved soft X-ray photoelectron spectroscopy Peer-reviewed

R. Yukawa, S. Yamamoto, K. Ozawa, M. Emori, M. Ogawa, Sh Yamamoto, K. Fujikawa, R. Hobara, S. Kitagawa, H. Daimon, H. Sakama, I. Matsuda

APPLIED PHYSICS LETTERS　105　(15)　2014/10

DOI： 10.1063/1.4897934 　

ISSN： 0003-6951

eISSN： 1077-3118
Non-linear kinetic model for oscillatory relaxation of the photovoltage effect on a Si(111)7 x 7 surface Peer-reviewed

M. Ogawa, R. -Y. Liu, C. -H. Lin, S. Yamamoto, R. Yukawa, R. Hobara, S. -J. Tang, I. Matsuda

SURFACE SCIENCE　624　70-75　2014/06

DOI： 10.1016/j.susc.2014.01.014 　

ISSN： 0039-6028

eISSN： 1879-2758
Electron-Hole Recombination Time at TiO2 Single-Crystal Surfaces: Influence of Surface Band Bending Peer-reviewed

Kenichi Ozawa, Masato Emori, Susumu Yamamoto, Ryu Yukawa, Shingo Yamamoto, Rei Hobara, Kazushi Fujikawa, Hiroshi Sakama, Iwao Matsuda

JOURNAL OF PHYSICAL CHEMISTRY LETTERS　5　(11)　1953-1957　2014/06

DOI： 10.1021/jz500770c 　

ISSN： 1948-7185
Observing hot carrier distribution in an n-type epitaxial graphene on a SiC substrate Peer-reviewed

T. Someya, H. Fukidome, Y. Ishida, R. Yoshida, T. Iimori, R. Yukawa, K. Akikubo, Sh Yamamoto, S. Yamamoto, T. Yamamoto, T. Kanai, K. Funakubo, M. Suemitsu, J. Itatani, F. Komori, S. Shin, I. Matsuda

APPLIED PHYSICS LETTERS　104　(16)　2014/04

DOI： 10.1063/1.4871381 　

ISSN： 0003-6951

eISSN： 1077-3118
Observation of a giant Kerr rotation in a ferromagnetic transition metal by M-edge resonant magneto-optic Kerr effect Peer-reviewed

Sh. Yamamoto, M. Taguchi, M. Fujisawa, R. Hobara, S. Yamamoto, K. Yaji, T. Nakamura, K. Fujikawa, R. Yukawa, T. Togashi, M. Yabashi, M. Tsunoda, S. Shin, I. Matsuda

PHYSICAL REVIEW B　89　(6)　2014/02

DOI： 10.1103/PhysRevB.89.064423 　

ISSN： 1098-0121

eISSN： 1550-235X
Relaxations of the surface photovoltage effect on the atomically controlled semiconductor surfaces studied by time-resolved photoemission spectroscopy Peer-reviewed

M. Ogawa, S. Yamamoto, K. Fujikawa, R. Hobara, R. Yukawa, Sh. Yamamoto, S. Kitagawa, D. Pierucci, M. G. Silly, C-H Lin, R-Y Liu, H. Daimon, F. Sirotti, S-J Tang, I. Matsuda

PHYSICAL REVIEW B　88　(16)　2013/10

DOI： 10.1103/PhysRevB.88.165313 　

ISSN： 1098-0121

eISSN： 1550-235X
Oscillatory relaxation of surface photovoltage on a silicon surface Peer-reviewed

M. Ogawa, S. Yamamoto, R. Yukawa, R. Hobara, C. H. Lin, R. Y. Liu, S. J. Tang, I. Matsuda

Physical Review B - Condensed Matter and Materials Physics　87　(23)　2013/06/17

DOI： 10.1103/PhysRevB.87.235308 　

ISSN： 1098-0121 1550-235X

eISSN： 1550-235X
Electronic structure of the hydrogen-adsorbed SrTiO3(001) surface studied by polarization-dependent photoemission spectroscopy Peer-reviewed

R. Yukawa, S. Yamamoto, K. Ozawa, M. D'Angelo, M. Ogawa, M. G. Silly, F. Sirotti, I. Matsuda

PHYSICAL REVIEW B　87　(11)　2013/03

DOI： 10.1103/PhysRevB.87.115314 　

ISSN： 1098-0121
Structural analysis of Si(111)-root 21 x root 21-(Ag, Cs) surface by reflection high-energy positron diffraction Peer-reviewed

Y. Fukaya, I. Matsuda, R. Yukawa, A. Kawasuso

SURFACE SCIENCE　606　(23-24)　1918-1921　2012/12

DOI： 10.1016/j.susc.2012.07.039 　

ISSN： 0039-6028
Hydrogen-Induced Surface Metallization of SrTiO3(001) Peer-reviewed

M. D'Angelo, R. Yukawa, K. Ozawa, S. Yamamoto, T. Hirahara, S. Hasegawa, M. G. Silly, F. Sirotti, I. Matsuda

PHYSICAL REVIEW LETTERS　108　(11)　2012/03

DOI： 10.1103/PhysRevLett.108.116802 　

ISSN： 0031-9007
Development of soft x-ray time-resolved photoemission spectroscopy system with a two-dimensional angle-resolved time-of-flight analyzer at SPring-8 BL07LSU Peer-reviewed

Manami Ogawa, Susumu Yamamoto, Yuka Kousa, Fumitaka Nakamura, Ryu Yukawa, Akiko Fukushima, Ayumi Harasawa, Hiroshi Kondoh, Yoshihito Tanaka, Akito Kakizaki, Iwao Matsuda

REVIEW OF SCIENTIFIC INSTRUMENTS　83　(2)　2012/02

DOI： 10.1063/1.3687428 　

ISSN： 0034-6748

eISSN： 1089-7623

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Misc. 20

空間反転対称な遍歴スキルミオン物質における電子構造

大東祐汰, KHANH N. D., 是常隆, 坂野昌人, 湯川龍, 堀場弘司, 組頭広志, 有馬孝尚, 有馬孝尚, 十倉好紀, 十倉好紀, 有田亮太郎, 有田亮太郎, 関真一郎, 石坂香子, 石坂香子

日本物理学会講演概要集(CD-ROM)　74　(2)　2019

ISSN： 2189-079X
in situ独立4探針STMを用いたSrTiO₃表面への水素照射の影響評価

武内康範, 秋山了太, 保原麗, 一ノ倉聖, 湯川龍, 松田巌, 長谷川修司

日本物理学会講演概要集(CD-ROM)　72　(1)　2017

ISSN： 2189-079X
水素終端したSrTiO₃表面の2次元伝導層の輸送特性

武内康範, 秋山了太, 保原麗, 高山あかり, 一ノ倉聖, 湯川龍, 松田巌, 長谷川修司

日本物理学会講演概要集(CD-ROM)　72　(2)　2017

ISSN： 2189-079X
Surface Photovoltage Effect and Photoexcited Carrier Dynamics in Space Charge Layer on TiO₂ Surfaces

Ozawa Kenichi, Yamamoto Susumu, Yukawa Ryu, Liu Roya, Emori Masato, Inoue Koki, Higuchi Taku, Sakama Hiroshi, Mase Kazuhiko, Matsuda Iwao

Meeting Abstracts of the Physical Society of Japan　72.1　2599-2599　2017
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.72.1.0_2599 　

eISSN： 2189-0803
Performance of wide energy range VUV-SX beamline KEK-PF BL-2 MUSASHI

Horiba Koji, Minohara Makoto, Mitsuhashi Taichi, Yukawa Ryu, Kitamura Miho, Kobayashi Masaki, Toyoshima Akio, Tanaka Hirokazu, Amemiya Kenta, Kumigashira Hiroshi

Meeting Abstracts of the Physical Society of Japan　71　(0)　1272-1272　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_1272 　

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KEK-PFの新ビームラインBL-2 MUSASHIは、長直線部に真空紫外（VUV: 30—300 eV）と軟X線（SX: 250—2,000 eV）との2台のアンジュレータをタンデム配置することで、30—2,000 eVの広範囲に渡って高エネルギー分解能かつ高フラックスの放射光を供給するVUV-SXビームラインとして、2015年度秋期より全国共同利用を開始している。本講演ではビームラインの性能および研究展開について紹介する。
Interfacial ferromagnetism at the heterointerface between perovskite oxides LaNiO₃ and LaMnO₃

Kitamura Miho, Horiba Koji, Kobayashi Masaki, Sakai Enju, Minohara Makoto, Yukawa Ryu, Mitsuhashi Taichi, Amemiya Kenta, Fujimori Atsushi, Fujioka Hiroshi, Kumigashira Hiroshi

Meeting Abstracts of the Physical Society of Japan　71　(0)　1275-1275　2016
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.71.2.0_1275 　

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酸化物へテロ界面では、構成物質単体では発現し得ないような特異な磁気特性が発現する。今回我々は、LaNiO_3_/LaMnO_3_ヘテロ界面において、X線磁気円二色性測定により元素選択的な界面磁化状態解析を行った結果、各酸化物単体の磁気特性とは異なる界面強磁性状態が実現していることを見出した。講演では、この起源について、前回報告したこのヘテロ界面における非対称な空間分布を有する界面電荷移動現象に基づいて議論する。
19pAJ-4 in situ angle-resolved photoelectron spectroscopy study on a two-dimensional electron-liquid at the Anatase-TiO_2(001) surface

Yukawa R, Minohara M, Mitsuhashi T, Kitamura M, Kobayashi M, Horiba K, Kumigashira H

Meeting Abstracts of the Physical Society of Japan　71　(0)　2495-2495　2016
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.71.1.0_2495 　

ISSN： 2189-079X
19pBM-6 Breakdown of Fermi Liquid near Metal-Insulator Transition in Strongly Correlated Oxide SrVO_3 Quantum Well

Kobayashi M, Yoshimatsu K, Mitsuhashi T, Sakai E, Kitamura M, Yukawa R, Minohara M, Fujimori A, Horiba K, Kumigashira H

Meeting Abstracts of the Physical Society of Japan　71　(0)　2024-2024　2016
Publisher: The Physical Society of Japan (JPS)
DOI： 10.11316/jpsgaiyo.71.1.0_2024 　

ISSN： 2189-079X
7aAJ-5 Recombination time of photoexcited carriers on single crystal TiO_2 surfaces

Ozawa Kenichi, Emori Masato, Yamamoto Susumu, Yukawa Ryu, Yamamoto Shingo, Hobara Rei, Fujikawa Kazushi, Sakama Hiroshi, Matsuda Iwao

Meeting abstracts of the Physical Society of Japan　69　(2)　501-501　2014/08/22
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28pCL-3 Observing carrier dynamics in an n-type epitaxial graphene using time-resolved photoemission spectroscopy

Someya T., Fukidome H., Ishida Y., Yoshida R., Iimori T., Yamamoto T., Yukawa R., Yamamoto Sh., Yamamoto S., Kanai T., Itatani J., Komori F., Shin S., Matsuda I.

Meeting abstracts of the Physical Society of Japan　69　(1)　710-710　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28aAS-3 Time-Resolved Photoemission Study of the Surface Photovoltage Effect on ZnO

Yukawa R., Yamamoto S., Ozawa K., Emori M., Ogawa M., Kitagawa S., Daimon H., Matsuda I.

Meeting abstracts of the Physical Society of Japan　69　(1)　741-741　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28pPSA-25 Development of vibration-isolated low-temperature manipulator for band mapping by soft x-ray photoemission spectroscopy

Akikubo K., Yamamoto S., Ogawa M., Hobara R., Yukawa R., Matsuda I.

Meeting abstracts of the Physical Society of Japan　69　(1)　883-883　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28pPSA-23 Relaxation process of surface photovoltage effect on the In/Si(111) surface revealed by time resolved soft X-ray photoelectron spectroscopy

Yamamoto S., Ogawa M., Fujikawa K., Hobara R., Yukawa R., Yamamoto Sh., Kitagawa S., Pierucci D., Silly M. G., Lin C.-H., Liu R.-Y., Daimon H., Sirotti F., Tang S.-J., Matsuda I.

Meeting abstracts of the Physical Society of Japan　69　(1)　883-883　2014/03/05
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Oscillatory relaxation of surface photovoltage on a silicon surface (vol 87, 235308, 2013)

M. Ogawa, S. Yamamoto, R. Yukawa, R. Hobara, C. -H. Lin, R. -Y. Liu, S. -J. Tang, I. Matsuda

PHYSICAL REVIEW B　89　(11)　2014/03

DOI： 10.1103/PhysRevB.89.119903 　

ISSN： 1098-0121

eISSN： 1550-235X
Relaxations of the surface photovoltage effect on the atomically controlled semiconductor surfaces studied by time-resolved photoemission spectroscopy (vol 88, 165313, 2013)

M. Ogawa, S. Yamamoto, K. Fujikawa, R. Hobara, R. Yukawa, Sh Yamamoto, S. Kitagawa, D. Pierucci, M. G. Silly, C. -H. Lin, R. -Y. Liu, H. Daimon, F. Sirotti, S. -J. Tang, I. Matsuda

PHYSICAL REVIEW B　89　(11)　2014/03

DOI： 10.1103/PhysRevB.89.119904 　

ISSN： 1098-0121

eISSN： 1550-235X
26pPSA-48 Carrier dynamics on oxide surfaces studied by time-resolved soft x-ray photoelectron spectroscopy

Yamamoto S., Yukawa R., Ogawa M., Fujikawa K., Yamamoto Sh., Hobara R., Matsuda I.

Meeting abstracts of the Physical Society of Japan　68　(1)　980-980　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
26pPSA-14 The surface electronic structure of Si(111)√<31>×√<31>-In and carrier dynamics

Fujikawa K., Ogawa M., Yamamoto S., Yukawa R., Silly M., Debora P., Sirotti F., Matsuda I.

Meeting abstracts of the Physical Society of Japan　68　(1)　973-973　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
26pEJ-10 Development of measurement system for magneto-optical effect with a vacuum ultraviolet SASE free electron laser

Yamamoto S., Fujisawa M., Hobara R., Yamamoto S., Nakamura T., Fujikawa K., Yukawa R., Taguchi M., Oura M., Togashi T., Tsunoda M., Shin S., Matsuda I.

Meeting abstracts of the Physical Society of Japan　68　(1)　801-801　2013/03/26
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23pPSB-35 Surface metallization of SrTiO_3(001) by adsorption of hydrogen

Yukawa R., Yamamoto S., D'angelo Marie, Ogawa M., Ozawa K., Kitagawa S., Daimon H., Matsuda I.

Meeting abstracts of the Physical Society of Japan　66　(2)　953-953　2011/08/24
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
26aHC-6 Development of Laser pump- Synchrotron Radiation probe soft X-ray time and angle resolved photoemission spectroscopy system

Ogawa Manami, Yamamoto Susumu, Kousa Yuka, Nakamura Fumitaka, Yukawa Ryu, Fukushima Akiko, Harasawa Ayumi, Kondo Hiroshi, Tanaka Yoshihito, Kakizaki Akito, Matsuda Iwao

Meeting abstracts of the Physical Society of Japan　66　(1)　772-772　2011/03/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349

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Books and Other Publications 8

若手研究者に紹介したいe-JSSNT の活用方法

長谷川友里, 武安光太郎, 湯川龍

日本表面真空学会表面と真空　2022/11
Thickness Dependence of Electronic and Crystal Structures in VO2 Ultrathin Films

D. Shiga, B. E. Yang, N. Hasegawa, T. Kanda, R. Tokunaga, K. Yoshimatsu, R. Yukawa, M. Kitamura, K. Horiba, H. Kumigashira

2021/04
Demonstration of Metal–Insulator Transition Induced by Resonant Tunneling in Double Quantum Well Structures of Strongly Correlated Oxides

R. Yukawa, M. Kobayashi, T. Kanda, D. Shiga, K. Yoshimatsu, S. Ishibashi, M. Minohara, M. Kitamura, K. Horiba, A. F. Santander-Syro, H. Kumigashira

2020/04
In situ Angle-Resolved Photoelectron Spectroscopy Studies of Two-Dimensional Electronic States at Anatase TiO2 (001) Surface Controlled by K Adsorption

R. Yukawa, M. Minohara, D. Shiga, M. Kitamura, T. Mitsuhashi, M. Kobayashi, K. Horiba, and H. Kumigashira

2019/04
強相関酸化物の金属量子井戸における量子臨界的挙動

小林正起 ,吉松公平,三橋太一,北村未歩,坂井延寿,湯川龍,簔原誠人,藤森淳,堀場弘司,組頭広志

PF NEWS Vol. 35, No. 4　2018/02
オンデマンド光機能酸化物ヘテロ構造とキャリアダイナミクス

湯川龍, 山本達, 松田巌

物性研だより第 57 巻第 3 号　2017/10
Controlling photovoltage responses at SrRuO3/SrTiO3 heterostructures

Ryu Yukawa, Susumu Yamamoto, Iwao Matsuda

2017/08
フランスの放射光施設 SOLEIL 利用報告

湯川龍

PF NEWS Vol. 29, No. 2　2011/09

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Research Projects 4

革新的異方キャリア伝導決定手法の開発による遷移金属酸化物上の１次元金属の解明

湯川龍, 庵智幸

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2023/04 - 2026/03
新奇転移機構探索のためのシートキャリアイメージングの実現

湯川龍

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 挑戦的研究(萌芽)

Institution: 東北大学

2023/06 - 2025/03
表面超構造・電子状態同時測定拠点の実現による表面電子状態の徹底解明

湯川龍, 望月出海, 大坪嘉之

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 大阪大学

2019/04 - 2023/03

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本研究は全反射高速陽電子線回折(TRHEPD)法を用いて表面の超構造を正確に決定し、角度分解光電子分光(ARPES)でその電子状態を徹底的に明らかにすることを目的としている。本年度はこれまでのアナターゼ型TiO2(4x1)の表面超構造の研究に加えて、新たに金属単結晶上に製膜した機能性金属酸化物の表面の表面超構造をTRHEPD法で測定し、さらに表面でのARPES測定を行った。作製した試料由来の分散を有する電子構造に加えて、表面超構造に起因したTRHEPDの回折パターンを得ることに成功した。本研究の発展に欠かせない超高真空内試料表面準備装置とその自動計測プログラムの追加設計を行うことで高真空下での4端子法による超伝導転移の測定に成功した。具体的には以下の研究を実施した。 1)超高真空下でのアナターゼ型TiO2(4x1)表面超構造を決定した。さらに酸素脱離の影響を調べるため酸素雰囲気化にて同表面のTRHEPD測定を実施した。 2)低速陽電子実験施設にて、超高真空下で清浄化した金属単結晶上に機能性酸化物薄膜をMBE法で作製した。電子線回折を用いて表面の結晶性を確認し、TRHEPD測定を行なった。その結果、表面超構造に起因したロッキング曲線形状の変化の観測に成功した。さらに本試料のARPES測定を実施し、製膜した酸化物由来の電子構造の測定に成功した。 3)超高真空内試料表面準備装置に新たに作製した4端子をとりつけ、自動計測プログラムを大幅に高機能化した。このことで、真空条件で試料の9 Kでの超伝導転移の測定に成功した。薄膜試料の条件出しの高度化が可能となった。
遷移金属酸化物における２次元電子系に働く多体間相互作用の解明 Competitive

湯川龍

Offer Organization: 日本学術振興会

System: 科学研究費補助金若手研究(B)

2017/04 - 2019/03

Teaching Experience 3

Informatics Basics for Natural-Science Major A　Osaka University
Experiments in Applied Physics　Osaka University
Exercise in Solid State Physics　Osaka University