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

2017 2016

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).