Topological Spintronics Research Unit

Principal Investigator

PI Name Yuki Shiomi
Degree D.Eng.
Title Unit Leader
Brief Resume
2012Assistant Professor, Advanced Institute for Materials Research, Tohoku University
2013Assistant Professor, Institute for Materials Research, Tohoku University
2017Lecturer, Quantum-Phase Electronics Center, University of Tokyo (-present)
2017Unit Leader, Topological Spintronics Research Unit, RIKEN Center for Emergent Matter Science (CEMS) (-present)

Outline

In our unit, we conduct basic research on spin electronics (spintronics) from the standpoint of condensed matter physics to aim for the development of a new principle applicable to next-generation spintronics devices. We focus on spin current which is an important component in spintronic devices, and explore novel spin-current phenomena using physical concepts and materials discovered recently in the field of condensed matter physics. In particular, in order to maximize the effects of the spin-orbit interaction which is important for controlling the spin property in a substance, we exploit the mathematical concept of topology in our spintronics research (topological spintronics).

Research Fields

Physics, Engineering

Keywords

Magnetism
Spintronics
Spin current
Topological insulator
Topological quantum matters
Berry phase physics
Edelstein effect

Results

Explore new spintronics phenomena using topological concepts

“Topological spintronics” is an emerging research field aiming at exploring new spintronic functions by effectively utilizing topological properties of materials. A representative material of interest is a 3D topological insulator. In a 2D surface state of a topological insulator, a Dirac-cone like dispersion relation and vortex like spin arrangement are realized. This special spin texture where the spin direction is always perpendicular to the momentum direction is called the spin-momentum locking, and highly promising for realizing highly efficient interconversion between charge and spin currents. Our state-of-the art experimental technique of spin current transport enables electrical detection of the spin-momentum locking. In bilayers of a topological insulator and a ferromagnetic metal, we have found evidence for an efficient spin-to-charge conversion on the surface states of topological insulators. We have also discussed the experimental results for some topological insulator samples with different properties of the topological surface transport, and revealed that the efficiency of the spin-to-charge conversion increases in proportion to the mean free path of the topological insulator surface.

(a) A schematic illustration of spin-current injection into topological insulator surfaces. (b) An example of experimental results. At magnetic fields where the spin current is injected into a topological insulator surface, voltage peaks due to spin-to-charge conversion appears.

Members

Yuki Shiomi

Unit Leader shiomi[at]riken.jp

お問い合わせ

2-1 Hirosawa, Wako, Saitama
#131 Main Research Building 351-0198 Japan

E-mail:
shiomi[at]riken.jp

Links