Advanced Spectroscopy Research Group

Japanese

Advanced Spectroscopy Research Group

Group Leader ISHII Kenji

Development of X-ray spectroscopic techniques for materials characterization
Synergistic use of SPring-8 (Hard X-ray) and NanoTerasu (Soft X-ray) 

Materials science by means of inelastic X-ray scattering and X-ray emission spectrosocpy 

We are conducting research that investigates the electronic states of materials using high-energy-resolution X-rays. The target materials range from strongly correlated electron systems like cuprate superconductors to functional materials such as battery electrodes and catalysts, where transition metals play an important role in their physical properties and functions. The element selectivity of X-ray spectroscopy is effective for elucidating the electronic states of the transition metals, and the high transmission capability of X-rays enables us to perform operando measurements of the functional materials.

Theoretical study of the resonant inelastic X-ray scattering on transition metal oxides 

We examine electronic states of transition metal oxides such as high-temperature superconductivity cuprates by using numerically exact diagonalization techniques and discuss spectra such as resonant inelastic X-ray scattering and photoemission spectroscopy.  In addition, the excitation spectra for the photoexcited state excited by the pump light are obtained by the numerical calculation, and their characteristics are clarified theoretically. 

Development and application of X-ray detected ferromagnetic resonance spectroscopy

In spintronics research to realize ultra-fast and ultra-low power computing and storage devices, it is very important to investigate the magnetic dynamics of materials. We are developing and applying X-ray detected ferromagnetic resonance (XFMR) spectroscopy, which enables element-specific investigation of such magnetic dynamics. 

1. Takuma Iwata, T. Kousa, Y. Nishioka, K. Ohwada, K. Sumida, E. Annese, M. Kakoki, Kenta Kuroda, H. Iwasawa, M. Arita, S. Kumar, A. Kimura, K. Miyamoto and T. Okuda, Laser-based angle-resolved photoemission spectroscopy with micrometer spatial resolution and detection of three-dimensional spin vector, Scientific Reports 14, 127 (2024).
2. ​Hideaki Iwasawa, Tetsuro Ueno, Yoshiyuki Yoshida, Hiroshi Eisaki, Yoshihiro Aiura, and Kenya Shimada, Quantitative measure of correlation strength among intertwined many-body interactions, Physical Review Research 5, 043266 (2023).
3. Norihiro Oshime, Kenji Ohwada, Akihiko Machida, Nagise Fukushima, Kosuke Shirakawa, Shintaro Ueno, Ichiro Fujii, Satoshi Wada, Kento Sugawara, Ayumu Shimada, Tetsuro Ueno, Tetsu Watanuki, Kenji Ishii, Hidenori Toyokawa, Koichi Momma, Sangwook Kim, Shinya Tsukada, Yoshihiro Kuroiwa, Lattice strain visualization inside a 400 nm single grain of BaTiO3 in polycrystalline ceramics by Bragg coherent X-ray diffraction imaging, Japanese Journal of Applied Physics 62, SM1022 (2023).
4. Hideaki Iwasawa, Kazuki Sumida, Shigeyuki Ishida, Patrick Le Fèvre, François Bertran, Yoshiyuki Yoshida, Hiroshi Eisaki, Andrés F. Santander-Syro, and Taichi Okuda, Exploring spin-polarization in Bi-based high-Tc cuprates, Scientific Reports 13, 13451 (2023).
5. Toshio Yamaguchi, Nami Fukuyama, Koji Yoshida, Yoshinori Katayama, Shinichi Machida, and Takanori Hattori, An X-ray and Neutron Scattering Study of Aqueous MgCl2 Solution in the Gigapascal Pressure Range, Liquids 3, 288 (2023).
6. Kenji Tsutsui, Kazuya Shinjo, and Takami Tohyama, Theoretical Study of the Time-Resolved Spin Excitation Spectrum in the Photoexcited Mott Insulator, JPS Conference Proceedings 38, 011159 (2023).
7. Yizhou Chen, Shun Asano, Tong Wang, Peiao Xie, Shinnosuke Kitayama, Kenji Ishii, Daiju Matsumura, Takuya Tsuji, Takanori Taniguchi, and Masaki Fujita, Cu K-edge X-ray Absorption Fine Structure Study of T′-type RE2CuO4+α−δ (RE = Rare Earth): Toward Unified Understanding of Electronic State of T′-type Cuprate, JPS Conference Proceedings 38, 011050 (2023).

1. Tetsuro Ueno and Hideaki Iwasawa, Measurement Informatics in Synchrotron Radiation X-ray Spectroscopy, Synchrotron Radiation News 35, 3 (2022).

1. Kenji Ishii (Co-author), “Resonant Inelastic X-Ray Scattering in Strongly Correlated Copper Oxides”, Resonant X-Ray Scattering in Correlated Systems, Springer (2017).

• Resonant Inelastic X-ray Scattering Spectroscopy Station (SPring-8 BL11XU)

1. JSPS KAKENHI Grant No. 22K03500 (FY2022–2024) (K. Tsutsui)
2. JSPS KAKENHI Grant No. 22K04915 (FY2022–2024) (T. Ueno)
3. JSPS KAKENHI Grant No. 21K19035 (FY2021–2022) (K. Ishii)