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High-resolution Spin- and Angle-resolved photoelectron spectroscopy with Laser Light at LASOR

Spin- and angle-resolved photoelectron spectroscopy (SARPES) is a powerful technique to investigate the spin-dependent electronic states in solids. From FY 2014, We started a project constructing new SARPES apparatus using laser light. Our new system is designed to provide high-energy and -angular resolution and high efficiency of spin detection for SARPES.The apparatus is equipped a high-energy resolution photoelectron analyzer (VG Scienta, D80 analyzer) with deflectors (VG Scienta, DA30L) and two high efficient spin detectors associating very low energy electron diffraction (VLEED), which allows us to analyze the three-dimensional spin polarization of electrons.

The electrons are excited with 6.994 eV photons, yielded by 6th harmonic of a Nd:YVO4 quasi-continuous wave laser with repetition rate of 80 MHz. A He discharge lamp (VG Scienta, VUV5000) is also available as a photon source. Samples are cooled by the liquid He cryostat below 9 K. The experiment station also consists of an MBE chamber and a carousel chamber connected to a load-lock chamber. The surface evaluating and preparing instruments, such as evaporators, LEED, RHEED, Sputter-gun, quartz microbalance can be installed. The new SARPES system is utilized to obtain precise information on spin-dependent electronic structures near the Fermi level in solids. Joint research at this station has been started from FY 2015.

Publication List

2024 2023 2022 2021 2020 2019 　 2018 2017 2016

Robust Weak Topological Insulator in the Bismuth Halide Bi4Br2⁢I2

Ryo Noguchi, Masaru Kobayashi, Kaishu Kawaguchi, Wataru Yamamori, Kohei Aido, Chun Lin, Hiroaki Tanaka, Kenta Kuroda, Ayumi Harasawa, Viktor Kandyba, Mattia Cattelan, Alexei Barinov, Makoto Hashimoto, Donghui Lu, Masayuki Ochi, Takao Sasagawa, and Takeshi Kondo

Phys. Rev. Lett. 133, 086602

DOI:https://doi.org/10.1103/PhysRevLett.133.086602

Spin-polarized saddle points in the topological surface states of elemental bismuth revealed by pump-probe spin- and angle-resolved photoemission spectroscopy

Yuto Fukushima, Kaishu Kawaguchi, Kenta Kuroda, Masayuki Ochi, Motoaki Hirayama, Ryo Mori, Hiroaki Tanaka, Ayumi Harasawa, Takushi Iimori, Zhigang Zhao, Shuntaro Tani, Koichiro Yaji, Shik Shin, Fumio Komori, Yohei Kobayashi, and Takeshi Kondo

Phys. Rev. B. 110, L041401

DOI:https://doi.org/10.1103/PhysRevB.110.L041401

Photoemission angular distribution beyond the single wavevector description of photoelectron final states

Hiroaki Tanaka, Shota Okazaki, Yuto Fukushima, Kaishu Kawaguchi, Ayumi Harasawa, Takushi Iimori, Fumio Komori, Masashi Arita, Ryo Mori, Kenta Kuroda, Takao Sasagawa, and Takeshi Kond

Phys. Rev. B. 109, L241114

DOI:https://doi.org/10.1103/PhysRevB.109.L241114

Time-, spin-, and angle-resolved photoemission spectroscopy with a 1-MHz 10.7-eV pulse laser

Kaishu Kawaguchi, Kenta Kuroda, Z. Zhao, S. Tani, A. Harasawa, Y. Fukushima, H. Tanaka, R. Noguchi, T. Iimori, K. Yaji, M. Fujisawa, S. Shin, F. Komori, Y. Kobayashi, and Takeshi Kondo

Rev. Sci. Instrum. 94, 083902 (2023)

https://doi.org/10.1063/5.0151859

Topological surface state of Bi2Se3 modified by physisorption of n-Alkane

Rena Moue, Hiroto Yamazaki, Tatsuya Kitazawa, Koichiro Yaji, Hiroshi Yaguchi, Kenta Kuroda, Takeshi Kondo, Ayumi Harasawa, Takashi Iwahashi, Yukio Ouchi, Shik Shin and Kaname Kanai

ChemNanoMat, 9, e202200538 (2023)

https://doi.org/10.1002/cnma.202200538

Enhanced Rashba Splitting of Au(111) Surface States with Hydrogen-Bonded Melamine-Based Organic Framework

Rena Moue, Yuta Kokubo, Kozo Mukai, Hirotaka Mizushima, Yuto Fukushima, Kaishu Kawaguchi, Takeshi Kondo, Ayumi Harasawa, Jun Yoshinobu, Kazuhiko Mase, Shik Shin, and Kaname Kanai

Adv. Mater. Interfaces, 2201102 (2022)

DOI: 10.1002/admi.2022011021

Anomalously large spin-dependent electron correlation in the nearly half-metallic ferromagnet CoS2

Hirokazu Fujiwara, Kensei Terashima, Junya Otsuki, Nayuta Takemori, Harald O. Jeschke, Takanori Wakita, Yuko Yano, Wataru Hosoda, Noriyuki Kataoka, Atsushi Teruya, Masashi Kakihana, Masato Hedo, Takao Nakama, Yoshichika flOnuki, Koichiro Yaji, Ayumi Harasawa , Kenta Kuroda, Shik Shin, Koji Horiba ,Hiroshi Kumigashira, Yuji Muraoka, and Takayoshi Yokoya

Phys. Rev. B,106, 085114 (2022)

DOI: 10.1103/PhysRevB.106.085114

Fluctuating spin-orbital texture of Rashba-split surface states in real and reciprocal space

Takuto Nakamura, Yoshiyuki Ohtsubo, Ayumi Harasawa, Koichiro Yaji, Shik Shin, Fumio Komori, and Shin-ichi Kimura

Phys. Rev. B,105, 235141 (2022)

DOI: 10.1103/PhysRevB.105.235141

Visualization of optical polarization transfer to photoelectron spin vector emitted from a spin-orbit coupled surface state

Kenta Kuroda, Koichiro Yaji, Ryo Noguchi, Ayumi Harasawa, Shik Shin, Takeshi Kondo, and Fumio Komori

Phys. Rev. B,105, L121106 (2022)

DOI: 10.1103/PhysRevB.105.L121106

Selective observation of surface and bulk bands in polar WTe2 by laser-based spin- and angle-resolved photoemission spectroscopy

Yuxuan Wan, Lihai Wang, Kenta Kuroda, Peng Zhang, Keisuke Koshiishi, Masahiro Suzuki, Jaewook Kim, Ryo Noguchi, Cédric Bareille, Koichiro Yaji, Ayumi Harasawa, Shik Shin, Sang-Wook Cheong, Atsushi Fujimori, and Takeshi Kondo

Phys. Rev. B,105, 085421 (2022)

Doi.org/10.1103/PhysRevB.105.085421

Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3

Chun Lin, Masayuki Ochi, Ryo Noguchi, Kenta Kuroda, Masahito Sakoda, Atsushi Nomura, Masakatsu Tsubota, Peng Zhang, Cedric Bareille, Kifu Kurokawa, Yosuke Arai, Kaishu Kawaguchi, Hiroaki Tanaka, Koichiro Yaji, Ayumi Harasawa, Makoto Hashimoto, Donghui Lu, Shik Shin, Ryotaro Arita, Satoshi Tanda & Takeshi Kondo

Nature Materials 20, 1093 (2021)

DOI:https://doi.org/10.1038/s41563-021-01004-4

Observation and control of the weak topological insulator state in ZrTe5

Peng Zhang, Ryo Noguchi, Kenta Kuroda, Chun Lin, Kaishu Kawaguchi, Koichiro Yaji, Ayumi Harasawa, Mikk Lippmaa, Simin Nie, Hongming Weng, V. Kandyba, A. Giampietri, A. Barinov, Qiang Li, G. D. Gu, Shik Shin & Takeshi Kondo

Nature Comm. 12, 406 (2021)

DOI:https://doi.org/10.1038/s41467-020-20564-8

Evidence for a higher-order topological insulator in a three-dimensional material built from van der Waals stacking of bismuth-halide chains.

Ryo Noguchi, Masaru Kobayashi, Zhanzhi Jiang, Kenta Kuroda, Takanari Takahashi, Zifan Xu, Daehun Lee, Motoaki Hirayama, Masayuki Ochi, Tetsuroh Shirasawa, Peng Zhang, Chun Lin, Cédric Bareille, Shunsuke Sakuragi, Hiroaki Tanaka, So Kunisada, Kifu Kurokawa, Koichiro Yaji, Ayumi Harasawa, Viktor Kandyba, Alessio Giampietri, Alexei Barinov, Timur K. Kim, Cephise Cacho, Makoto Hashimoto, Donghui Lu, Shik Shin, Ryotaro Arita, Keji Lai, Takao Sasagawa, Takeshi Kondo

Nature Materials 20, 473 (2021).

DOI:https://doi.org/10.1038/s41563-020-00871-7

Structure and electronic structure of van der Waals interfaces at a Au(111) surface covered with a well-ordered molecular layer of n-alkanes

Hirotaka Mizushima, Harunobu Koike, Kenta Kuroda, Koichiro Yaji, Ayumi Harasawa, Yukiaki Ishida, Mitsuhiro Nakayama, Kazuhiko Mase, Kozo, Mukai, Tatsuya Kitazawa, Takeshi Kondo, Jun Yoshinobu, Shik Shin, Kaname Kanai

Applied Surface Science 535, 147673 (2021)

DOI:https://doi.org/10.1016/j.apsusc.2020.147673

Fully spin-polarized bulk states in ferroelectric GeTe

Juraj Krempaský, Mauro Fanciulli, Laurent Nicolaï, Jan Minár, Henrieta Volfová, Ondřej Caha, Valentine V. Volobuev, Jaime Sánchez-Barriga, Martin Gmitra, Koichiro Yaji, Kenta Kuroda, Shik Shin, Fumio Komori, Gunther Springholz, and J. Hugo Dil

Phys. Rev. Research 2, 13107 (2020)

DOI:https://doi.org/10.1103/PhysRevResearch.2.013107

Orbital Angular Momentum Induced Spin Polarization of 2D Metallic Bands

Takahiro Kobayashi, Yoshitaka Nakata, Koichiro Yaji, Tatsuya Shishidou, Daniel Agterberg, Shunsuke Yoshizawa, Fumio Komori, Shik Shin, Michael Weinert, Takashi Uchihashi, and Kazuyuki Sakamoto

Phys. Rev. Lett. 125, 176401 (2020)

DOI:https://doi.org/10.1103/PhysRevLett.125.176401

Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi2Te4

A. M. Shikin, D. A. Estyunin, I. I. Klimovskikh, S. O. Filnov, E. F. Schwier, S. Kumar, K. Miyamoto, T. Okuda, A. Kimura, K. Kuroda, K. Yaji, S. Shin, Y. Takeda, Y. Saitoh, Z. S. Aliev, N. T. Mamedov, I. R. Amiraslanov, M. B. Babanly, M. M. Otrokov, S. V. Eremeev & E. V. Chulkov

Scientific Reports (2020) 10, 13226 (2020)

Topological surface state of Bi2Se3 modified by adsorption of organic donor molecule tetrathianaphthacene

T. Kitazawa, K. Yaji, K. Shimozawa, H. Kondo, T. Yamanaka, H. Yaguchi, Y. Ishida, K. Kuroda, A. Harasawa, T. Iwahashi, Y. Ouchi, F. Komori, S. Shin, K. Kanai

Adv. Mater. Interfaces 7, 2000524 (2020)

DOI: 10.1002/admi.202000524

Unified description of the electronic structure of M2AC nanolamellar carbides

Damir Pinek, Takahiro Ito, Masashi Ikemoto, Koichiro Yaji, Masashi Nakatake, Shik Shin, and Thierry Ouisse

Phys. Rev. B 100, 075144 (2019)

DOI:10.1103/PhysRevB.100.075144

Giant Rashba system on a semiconductor substrate with tunable Fermi level: Bi/GaSb(110)–(2×1)

Takuto Nakamura, Yoshiyuki Ohtsubo, Naoki Tokumasu, Patrick Le Fèvre, François Bertran, Shin-ichiro Ideta, Kiyohisa Tanaka, Kenta Kuroda, Koichiro Yaji, Ayumi Harasawa, Shik Shin, Fumio Komori, and Shin-ichi Kimura

Phys. Rev. Materials 3, 126001 (2019)

DOI: 10.1103/PhysRevMaterials.3.126001

Coexistence of Two Types of Spin Splitting Originating from Different Symmetries

Koichiro Yaji, Anton Visikovskiy, Takushi Iimori, Kenta Kuroda, Singo Hayashi, Takashi Kajiwara, Satoru Tanaka, Fumio Komori, and Shik Shin

Phys. Rev.Lett. 122, 126403 (2019)

A weak topological insulator state in quasi-one-dimensional bismuth iodide

Ryo Noguchi, T. Takahashi, K. Kuroda, M. Ochi, T. Shirasawa, M. Sakano, C. Bareille, M. Nakayama, M. D. Watson, K. Yaji, A. Harasawa, H. Iwasawa, P. Dudin, T. K. Kim, M. Hoesch, V. Kandyba, A. Giampietri, A. Barinov, S. Shin, R. Arita, T. Sasagawa & Takeshi Kondo

Nature 566,518(2019)

DOI: 10.1038/s41586-019-0927-7

Multiple topological states in iron-based superconductors

Peng Zhang, Zhijun Wang, Xianxin Wu, Koichiro Yaji, Yukiaki Ishida, Yoshimitsu Kohama, Guangyang Dai, Yue Sun, Cedric Bareille, Kenta Kuroda, Takeshi Kondo, Kozo Okazaki, Koichi Kindo, Xiancheng Wang, Changqing Jin, Jiangping Hu, Ronny Thomale, Kazuki Sumida, Shilong Wu, Koji Miyamoto, Taichi Okuda, Hong Ding, G. D. Gu, Tsuyoshi Tamegai, Takuto Kawakami, Masatoshi Sato & Shik Shin

Nature Physics 15, 41-47 (2019).

Origins of Thermal Spin Depolarization in Half-Metallic Ferromagnet CrO2

Hirokazu Fujiwara, Kensei Terashima, Masanori Sunagawa, Yuko Yano, Takanobu Nagayama, Tetsushi Fukura, Fumiya Yoshii, Yuka Matsuura, Makoto Ogata, Takanori Wakita, Koichiro Yaji, Ayumi Harasawa, Kenta Kuroda, Shik Shin, Koji Horiba, Hiroshi Kumigashira, Yuji Muraoka, and Takayoshi Yokoya

Phys. Rev. Lett. 121, 2572201 (2018).

Giant Rashba splitting of quasi-one-dimensional surface states on Bi/InAs(110)-(2×1)

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

Phys. Rev. B 98, 075431 (2018).

Rashba spin splitting of L-gap surface states on Ag(111) and Cu(111)

Koichiro Yaji, Ayumi Harasawa, Kenta Kuroda, Ronghan Li, Binghai Yan, Fumio Komori, and Shik Shin

Phys. Rev. B 98, 041404(R) (2018).

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser (Video Jounal)

Kenta Kuroda, Koichiro Yaji, Ayumi Harasawa, Ryo Noguchi, Takeshi Kondo, Fumio Komori, Shik Shin

J. Vis. Exp.,136, e57090,doi:10.3791/57090 (2018).

Optical spin control in photoexcitation process revealed by laser-based spin- and angle-resolved photoelectron spectroscopy (in Japanese)

Koichiro Yaji, Kenta Kuroda, Fumio Komori, Shik Shin

Japanese Journal of Optics, 47, 142-147,(2018).

Observation of topological superconductivity on the surface of iron-based superconductor

Peng Zhang, Koichiro Yaji, Takahiro Hashimoto, Yuichi Ota, Takeshi Kondo, Kozo Okazaki, Zhijun Wang, Jinsheng Wen, G. D. Gu, Hong Ding, and Shik Shin

Science 360, 182-186 (2018).

Optical spin control of photoexcited electrons using a polarization-controllable laser (in Japanese)

Koichiro Yaji, Kenta Kuroda, Fumio Komori, Shik Shin

Journal of Japan Laser Processing Society 25 , 39 (2018).

Surface electronic states of Au-induced nanowires on Ge(001)

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

J. Phys.: Condens. Matter 30, 075001 (2018).

Spin-polarized quasi 1D state with fintie bandgap on the Bi/InSb(001) surface

J. Kishi, Y. Ohtsubo, K. Yaji, A. Harasawa, F. Komori, S. Shin, J. E. Rault, P. Le Févre, F. Bertran, A. Taleb-Ibrahimi, M. Nurmamat, H. Yamane, S. Ideta, K. Tanaka, and S. Kimura

Phys. Rev. Mat., 1, 064602 (2017).

Spin-orital entanglement in surface states and optical spin control (in Japanese)

K. Yaji, K. Kuroda, F. Komori, S. Shin

Solid State Physics, 52, 559. (2017)

Modulation of electron-phonon coupling in periodically-nanorippled graphene on a macrofacet of 6H-SiC

Koichiro Ienaga, Takushi Iimori, Koichiro Yaji, Toshio Miyamachi, Shuhei Nakashima, Yukio Takahashi, Kohei Fukuma, Shingo Hayashi, Takashi Kajiwara, Anton Visikovsliy, Kazuhiko Mase, Kan Nakatsuji, Satoru Tanaka, and Fumio Komori

Nano Letters 17, 3527 (2017).

Experimental evidence of hourglass fermion in the candidate nonsymmorphic topological insulator KHgSb

Junzhang Ma, Changjiang Yi, Baiqing Lv, Zhijun Wang, Simin Nie, Le Wang, Lingyuan Kong, Yaobo Huang, Pierre Richard, Peng Zhang, Koichiro Yaji, Kenta Kuroda, Shik Shin, HongmingWeng, Bogdan Andrei Bernevig, Youguo Shi, Tian Qian, Hong Ding

Science Advances 3, e1602415(2017).

Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe2

M. Sakano, M. S. Bahramy, H. Tsuji, I. Araya, K. Ikeura, H. Sakai, S. Ishiwata, K. Yaji, K. Kuroda, A. Harasawa, S. Shin, and K. Ishizaka

Phys. Rev. B 95, 121101(R) (2017).

Spin-dependent quantum interference in photoemission process from spin-orbit coupled states

Koichiro Yaji, Kenta Kuroda, Sogen Toyohisa, Ayumi Harasawa, Yukiaki Ishida, Shuntaro Watanabe, Chuangtian Chen, Katsuyoshi Kobayashi, Fumio Komori & Shik Shin

Nature Communications 8, 14588 (2017)

Topologically Entangled Rashba-Split Shockley States on the Surface of Grey Arsenic

Peng Zhang, J.-Z. Ma, Y. Ishida, L.-X. Zhao, Q.-N. Xu, B.-Q. Lv, K. Yaji, G.-F. Chen, H.-M. Weng, X. Dai, Z. Fang, X.-Q. Chen, L. Fu, T. Qian, H. Ding, and S. Shin

Phys. Rev. Lett. 118, 046802 (2017)

Direct mapping of spin and orbital entangled wave functions under interband spin-orbit coupling of giant Rashba spin-split surface states

Ryo Noguchi, Kenta Kuroda, K. Yaji, K. Kobayashi, M. Sakano, A. Harasawa, Takeshi Kondo, F. Komori, and S. Shin

Phys. Rev. B 95, 041111(R) (2017)

Spin texture in type-II Weyl semimetal WTe2

Baojie Feng, Yang-Hao Chan, Ya Feng, Ro-Ya Liu, Mei-Yin Chou, Kenta Kuroda, Koichiro Yaji, Ayumi Harasawa, Paolo Moras, Alexei Barinov, Walid Malaeb, Cédric Bareille, Takeshi Kondo, Shik Shin, Fumio Komori, Tai-Chang Chiang, Youguo Shi, and Iwao Matsuda

Phys. Rev. B 94, 195134 (2016).

Coherent control over three-dimensional spin polarization for the spin-orbit coupled surface state of Bi2Se 3

Kenta Kuroda, Koichiro Yaji, M. Nakayama, A. Harasawa, Y. Ishida, S. Watanabe, C.-T. Chen, T. Kondo, F. Komori, and S. Shin

Phys. Rev. B 94, 165162 (2016).

One-dimensional metallic surface states of Pt-induced atomic nanowires on Ge(001)

Koichiro Yaji, Sunghun Kim, Izumi Mochizuki, Yasuo Takeichi, Yoshiyuki Ohtsubo, Patrick Le Fèvre, François Bertran, Amina Taleb-Ibrahimi, Shik Shin and Fumio Komori

J. Phys.: Condens. Matter 28, :274001 (2016).

High-resolution three-dimensional spin- and angle-resolved photoelectron spectrometer using vacuum ultraviolet laser light

Koichiro Yaji, Ayumi Harasawa, Kenta Kuroda, Sogen Toyohisa, Mitsuhiro Nakayama, Yukiaki Ishida, Akiko Fukushima1 Shuntaro Watanabe, Chuangtian Chen, Fumio Komori and Shik Shin

Rev. Sci. Instrum. 87, 053111(2016).

Development of spin- and angle-resolved photoelectron spectroscopy with laser light (In Japanese)

Yaji, Koichiro

Journal of the surface sciense society of Japan 37, 19 (2016) .

Spin polarization and texture of the Fermi arcs in the Weyl Fermion semimetal TaAs

S.-Y.Xu, I.Belopolski, D.S.Sanchez, M.Neupane, G.Chang, K.Yaji, Z. Yuan, C. Zhang, K.Kuroda, G. Bian, C. Guo, H. Lu, Y. Feng, T.-R. Chang, N. Alidoust, H. Zheng, C.-C. Lee, S.-M. Huang, C.-H. Hsu, Horng-Tay Jeng, A. Bansil, A. Alexandradinata, T. Neupert, T. Kondo, S.Shin, H.Lin, S.Jia, M Z.Hasan

Phys. Rev. Lett. 116, 096801 (2016).