Strong Correlation Physics Research Group

Principal Investigator

PI Name Yoshinori Tokura
Degree D.Eng.
Title Group Director
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, Strong Correlation Physics Division, RIKEN CEMS (-present)
2017Distinguished Professor, University of Tokyo (-present)

Outline

Our group investigates a variety of emergent phenomena in strongly correlated electron systems, which cannot be understood within the framework of conventional semiconductor/metal physics, to construct a new scheme of science and technology. In particular, we focus on transport, dielectric and optical properties in non-trivial spin/orbital structures, aiming at clarifying the correlation between the response and the spin/orbital state. In addition, we investigate electron systems with strong relativistic spin-orbit interaction, unraveling its impact on transport phenomena and other electronic properties. Target materials include high-temperature superconductors, colossal magnetoresistance systems, multiferroics, topological insulators, and skyrmion materials.

Research Fields

Physics, Engineering, Materials Sciences

Keywords

Strongly correlated electron system
Topological insulators
Spin-orbit interaction
Berry phase physics
Multiferroics
Skyrmion

Results

Topological spin textures and emergent electromagnetic functions

Nanometric spin texture called “skyrmion”. The skyrmion is the idea coined by Tony Skyrme, a nuclear physicist, to describe a state of nucleon as the topological soliton, It has recently been demonstrated that such a kind of topological particle should exist widely in ubiquitous magnetic solids. The arrows in the figure represent the directions of the spin (electron’s magnetic moment); the spins direct up at the peripheral, swirl in going to the inside, and direct down at the core. This topology cannot be reached via continuous deformation from the conventional spin orders, meaning that the skyrmion can be viewed by a topologically protected particle.  The skyrmion can carry a fictitious (emergent) magnetic field working on moving conduction electrons (represented by yellow balls), and hence causes the topological Hall effect (transverse drift of the current). Furthermore, the electric current itself can drive the skyrmion. The critical current density for the drive of skyrmions is around 100A/cm2,  by five orders of magnitude smaller than the conventional value for the drive of magnetic domain walls. These features may favor the application of skyrmions to innovative spintronics, i.e. toward “skyrmionics”.

Skyrmion and conduction electron motion

Skyrmion and conduction electron motion

Members

Yoshinori Tokura

Group Director tokura[at]riken.jp R

Yoshio Kaneko

Senior Technical Scientist

Chieko Terakura

Technical Scientist terakura[at]riken.jp R

Ryoma Kaneko

Junior Research Associate

Masakazu Ichikawa

Research Consultant

Yoshio Matsui

Senior Visiting Scientist

Yasushi Ogimoto

Senior Visiting Scientist

Articles

お問い合わせ

2-1 Hirosawa, Wako, Saitama 351-0198 Japan

E-mail:
tokura[at]riken.jp

Links