Centers & Labs

RIKEN Center for Emergent Matter Science

Electronic States Spectroscopy Research Team

Team Leader: Kyoko Ishizaka (Ph.D.)
Kyoko  Ishizaka(Ph.D.)

We investigate spin, electron, and crystal structures of materials showing a variety of physical properties, functions, and quantum phenomena. We use spin- and angle-resolved photoemission spectroscopy, which can probe the energy, momentum, and spin of electrons in solids, to study new materials and phenomena such as superconductors, thermoelectric / spintronic materials, topological quantum states, and many-body effects in strongly correlated systems. We are also starting a project on the ultrafast time-resolved transmission electron microscope utilizing pulsed lasers. Dynamics of spin, electron, and crystal structures in nanometer and femto-nanosecond scales will be explored.

Main Research Field

Mathematical and physical sciences

Related Research Fields

Interdisciplinary science and engineering


  • Photoemission Spectroscopy
  • Ultrafast TEM
  • Nano-scale magnetism
  • Superconductivity
  • Strongly correlated system

Selected Publications

Papers with an asterisk(*) are based on research conducted outside of RIKEN.
  1. *Suzuki, Y., Shimojima, T., Sonobe, T., Nakamura, A., Sakano, M., Tsuji, H., Omachi, J., Yoshioka, K., Kuwata-Gonokami, M., Watashige, T., Kobayashi, R., Kasahara, S., Shibauchi, T., Matsuda, Y., Yamakawa, Y., Kontani, H., and Ishizaka K.:
    "Momentum-dependent sign inversion of orbital order in superconducting FeSe"
    Phys. Rev. B 92, 205117 (2015)
  2. *Sakano, M., Okawa, K., Kanou, M., Sanjo, H., Okuda, T., Sasagawa, T., Ishizaka, K.:
    "Topologically protected surface states in a centrosymmetric superconductor β-PdBi2"
    Nat. Commun. 6, 8595 (2015)
  3. Suzuki, R., Sakano, M., Zhang, Y. J., Akashi, R., Morikawa, D., Harasawa, A., Yaji, K., Kuroda, K., Miyamoto, K., Okuda, T., Ishizaka, K., Arita, R., and Iwasa, Y.:
    "Valley-dependent spin polarization in bulk MoS2 with broken inversion symmetry"
    Nat. Nanotech. 9, 611 (2014)
  4. Sakano, M., Bahramy, M. S., Katayama, A., Shimojima, T., Murakawa, H., Kaneko, Y., Malaeb, W., Shin, S., Ono, K., Kumigashira, H., Arita, R., Nagaosa, N., Hwang, H. Y., Tokura, Y., and Ishizaka, K.:
    "Strongly Spin-Orbit Coupled Two-Dimensional Electron Gas Emerging near the Surface of Polar Semiconductors"
    Phys. Rev. Lett. 110, 107204 (2013)
  5. Ishizaka, K., Bahramy, M. S., Murakawa, H., Sakano, M., Shimojima, T., Sonobe, T., Koizumi, K., Shin, S., Miyahara, H., Kimura, A., Miyamoto, K., Okuda, T., Namatame, H., Taniguchi, M., Arita, R., Nagaosa, N., Kobayashi, K., Murakami, Y., Kumai, R., Kaneko, Y., Onose, Y., and Tokura, Y.:
    "Giant Rashba-type spin splitting in bulk BiTeI"
    Nat. Mater. 10, 521 (2011)
  6. Sakano, M., Bahramy, M. S., Tsuji, H., Araya, I., Ikeura, K., Sakai, H., Ishiwata, S., Yaji, K., Kuroda, K., Harasawa, A., Shin, S., and Ishizaka, K.:
    "Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe2",
    Phys. Rev. B 95, 121101(R)-1-6 (2017).
  7. *Nakamura, A., Shimojima, T., Sonobe, T., Yoshida, S., Ishizaka, K., Malaeb, W., Shin, S., Iimura, S., Matsuishi, S., and Hosono, H.:
    "Multiple-pseudogap phases in the hydrogen-doped LaFeAsO system"
    Phys. Rev. B 95, 064501-1-7 (2017).
  8. *Nakamura, A., Shimojima, T., Nakano, M., Iwasa, Y., and Ishizaka, K.:
    "Electron and lattice dynamics of transition metal thin films observed by ultrafast electron diffraction and transient optical measurements"
    Struct, Dyn. 3, 064501-1-10 (2016).
  9. *Shimojima, T., Suzuki, Y., Sonobe, T., Nakamura, A., Sakano, M., Omachi, J., Yoshioka, K., Kuwata- Gonokami, M., Ono, K., Kumigashira, H., B¨ohmer, A. E., Hardy, F., Wolf, T., Meingast, C., L¨ohneysen, H. v., Ikeda, H. and Ishizaka, K.:
    "Lifting of xz/yz orbital degeneracy at the structural transition in detwinned FeSe"
    Phys. Rev. B 90, 121111(R)-1-5 (2014)
  10. *Shimojima, T., Sakaguchi, F., Ishizaka, K., Ishida, Y., Kiss, T., Okawa, M., Togashi, T., Chen, Watanabe, S., Arita, M., Shimada, K., Namatame, H., Taniguchi, M., Ohgushi, K., Kasahara, S., Terashima, T., Shibauchi, T., Matsuda, Y., Chainani, A., and Shin, S.:
    "Orbital-Independent Superconducting Gaps in Iron-Pnictides"
    Science 332, 564-567 (2011).

Lab Members

Principal Investigator

Kyoko Ishizaka
Team Leader

Core Members

Takahiro Shimojima
Research Scientist
Asuka Nakamura
Special Postdoctoral Researcher

Contact information

304-1, Frontier Research Laboratory
2-1 Hirosawa,
Wako, Saitama
351-0198, Japan
Tel: +81-(0)48-467-4492
Fax: +81-(0)48-462-1687

Email: kyoko.ishizaka [at]

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