Strong Correlation Quantum Transport Research Team

Principal Investigator

PI Name Yoshinori Tokura
Degree D.Eng.
Title Team Leader
Brief Resume
1981D. Eng., University of Tokyo
1986Associate Professor, University of Tokyo
1994Professor, Department of Physics, University of Tokyo
1995Professor, Department of Applied Physics, University of Tokyo (-present)
2001Director, Correlated Electron Research Center, AIST
2007Group Director, Cross-Correlated Materials Research Group, RIKEN
2008AIST Fellow, National Institute of Advanced Industrial Science and Technology (-present)
2010Director, Emergent Materials Department, RIKEN
2010Group Director, Correlated Electron Research Group, RIKEN
2013Director, RIKEN Center for Emergent Matter Science (CEMS) (-present)
2013Group Director, Strong Correlation Physics Research Group, Strong Correlation Physics Division, RIKEN CEMS (-present)
2014Team Leader, Strong Correlation Quantum Transport Research Team, RIKEN CEMS (-present)
2019Distinguished University Professor, University of Tokyo (-present)

Outline

We study various kinds of quantum transport phenomena which emerge in bulk materials and at hetero-interfaces of thin films, focusing on electron systems with strong correlation and/or strong spin-orbit interactions. Specifically, we try to clarify quantum states of Dirac electrons at surface/interfaces of topological insulators as well as in bulk Rashba system with broken inversion symmetry, by observing Landau level formation, quantum (anomalous) Hall effect, and various quantum oscillation phenomena at low temperatures and in high magnetic fields. Also, we synthesize high-temperature superconducting cuprates in bulk forms and various transition-metal oxides thin films, and measure transport properties under high pressure or high magnetic-field, aiming at increasing superconducting transition temperature and at finding novel magneto-transport properties.

Research Fields

Physics, Engineering, Materials Science

Keywords

Strongly correlated electron system
High-temperature superconductor
Spin-orbit interaction
Topological insulators
Interface electronic structure

Results

Quantum transport phenomena of surface Dirac states in thin film superstructures

The topological insulator is a new state of matter, whose bulk is a three-dimensional charge-gapped insulator but whose surface hosts a two-dimensional Dirac electron state. Surface Dirac states are characterized by massless electrons and holes whose spins are polarized perpendicular to their crystal momentum. As a result, the quantum transport phenomena stemming from their charge and spin degrees of freedom are promising for the applications to low-power consumption electronic devices. The well-known example for this is the quantum anomalous Hall effect (QAHE) in which one-dimensional conducting channel without any dissipation emerges at zero magnetic field. We established the growth of high quality thin film superstructure of topological insulator (BixSb1-x)2Te3 sandwiched by ferromagnetic insulator (Zn,Cr)Te, by means of molecular beam epitaxy (MBE) method. We cooled down to cryogenic temperature, and successfully observed QAHE. We will make full use of the thin film superstructure to add functionality to topological materials. In particular, we now embark on the observation or control of the Majorana quasiparticle, which is expected to be applied to quantum computers.

Schematic of the quantum Hall effect on the surface of a topological insulator.

Members

Yoshinori Tokura

Team Leader tokura[at]riken.jp R

Yoshichika Onuki

Senior Research Scientist

Minoru Kawamura

Senior Research Scientist
Ryutaro Yoshimi Research Scientist ryutaro.yoshimi[at]riken.jp R

Ilya Boris Belopolski

Special Postdoctoral Researcher

Yuki Sato

Special Postdoctoral Researcher

Ayako Yamamoto

Visiting Scientist

Publications

  1. K. Yasuda, T. Morimoto, R. Yoshimi, M. Mogi, A. Tsukazaki, M. Kawamura, K. S. Takahashi, M. Kawasaki, N. Nagaosa , and Y. Tokura

    Large non-reciprocal charge transport mediated by quantum anomalous Hall edge states

    Nat. Nanotechnol. 15, 831 (2020)
  2. K. Yasuda, H. Yasuda, T. Liang, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, N. Nagaosa, M. Kawasaki, and Y. Tokura

    Nonreciprocal charge transport at topological insulator/superconductor interface

    Nat. Commun. 10, 2734 (2019)
  3. R. Yoshimi, K. Yasuda, A. Tsukazaki, K. S. Takahashi, M. Kawasaki, and Y. Tokura

    Current-driven magnetization switching in ferromagnetic bulk Rashba semiconductor (Ge,Mn)Te

    Sci. Adv. 4, aat9989 (2018)
  4. K. Yasuda, M. Mogi, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, M. Kawasaki, F. Kagawa, and Y. Tokura

    Quantized chiral edge conduction on domain walls of a magnetic topological insulator

    Science 358, 1311 (2017)
  5. M. Kawamura, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, M. Kawasaki, and Y. Tokura

    Current-Driven Instability of the Quantum Anomalous Hall Effect in Ferromagnetic Topological Insulators

    Phys. Rev. Lett. 119, 016803 (2017)

Articles

お問い合わせ

  

E-mail:
tokura[at]riken.jp

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