Quantum Matter Theory Research Team

Principal Investigator

PI Name Akira Furusaki
Degree D.Sci.
Title Team Leader
Brief Resume
1991Research Associate, Department of Applied Physics, University of Tokyo
1993Ph.D., University of Tokyo
1993Postdoctoral Associate, Massachusetts Institute of Technology, USA
1995Research Associate, Department of Applied Physics, University of Tokyo
1996Associate Professor, Yukawa Institute for Theoretical Physics, Kyoto University
2003Chief Scientist, Condensed Matter Theory Laboratory, RIKEN (-present)
2013Team Leader, Quantum Matter Theory Research Team, Strong Correlation Physics Division, RIKEN Center for Emergent Matter Science (-present)

Outline

We investigate novel quantum phases of many-electron systems in solids which emerge as a result of strong electron correlation and quantum effects. We theoretically study electronic properties of these new phases (such as transport and magnetism) and critical phenomena at phase transitions. Specifically, we study topological insulators and superconductors, frustrated quantum magnets, and other strongly correlated electron systems in transition metal oxides and molecular conductors, etc. We construct effective models for electrons in these materials and unveil their various emergent phases by solving quantum statistical mechanics of these models using both analytical and numerical methods.

Research Fields

Physics, Materials Sciences

Keywords

Electron correlation
Frustrated quantum magnets
Topological insulators
Superconductivity

Results

Classifying topological insulators and topological superconductors

Modern electronics is based on the band theory that describes quantum mechanical motion of electrons in a solid. The band theory can explain properties of metals, insulators and semiconductors, and led to the invention of transistors. However, recent studies revealed some important physics which was missed in the standard band theory. Namely, the geometric (Berry) phase of electron wave functions can have a nontrivial topological structure in momentum space, and this leads to a topological insulator. In addition, superconductors with gapped quasiparticle excitations can be a topological superconductor. In principle there are various types of topological insulators (TIs) and topological superconductors (TSCs) in nature.

We constructed a general theory that can classify TIs and TSCs in terms of generic symmetries.  This theory shows that in every spatial dimension there are three types of TIs/TSCs with an integer topological index and two types of TIs/TSCs with a binary topological index. Furthermore, we developed a theory classifying TIs/TSCs with a mirror symmetry.

A coffee mug and a donut are equivalent in topology because they can be continuously deformed from one to the other.

Members

Akira Furusaki

Team Leader furusaki[at]riken.jp R

Tsutomu Momoi

Senior Research Scientist

Shigeki Onoda

Senior Research Scientist

Hitoshi Seo

Senior Research Scientist

Yusuke Horinouchi

Special Postdoctoral Researcher

John Owen Benton

Postdoctoral Researcher

Articles

  • Oct 28, 2016 RIKEN RESEARCH The search for disorder in order
    A signature of an exotic state of matter that remains disordered even at very low temperatures has been experimentally identified
  • Nov 20, 2015 RIKEN RESEARCH Melting of frozen frustrations
    Computations reveal how quantum interactions can break a deadlock in magnetic spin ice oxides
  • Nov 13, 2015 RIKEN RESEARCH Mind the gap!
    Scanning tunneling microscopy is used to probe electrons in an unconventional superconductor, and uncovers an unexpected energy gap
  • Sep 04, 2015 RIKEN RESEARCH Spins on the edge
    The edges of thin films could provide an ideal laboratory for studying the behavior of electron spins
  • Mar 20, 2014 RIKEN RESEARCH Unraveling a quantum phase transition
    Phase transitions between different states of matter are normally driven by random thermal motions of atoms. However, when phase transitions occur at temperatures approaching absolute zero, quant ....

お問い合わせ

3F Main Research Building, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan

E-mail:
furusaki[at]riken.jp

Links