Quantum Nano-Scale Magnetism Research Team

Principal Investigator

PI Name Yoshichika Otani
Degree D.Sci.
Title Team Leader
Brief Resume
1989D.Sci.,Department of Physics, Keio University
1989Research Fellow, Trinity College University of Dublin, Ireland
1991Postdoctoral Researcher, Laboratoire Louis Néel, CNRS, France
1992Research Instructor, Keio University
1995Associate Professor, Tohoku University
2001Team Leader, Quantum Nano-Scale Magnetics Team, RIKEN
2004Professor,  ISSP University of Tokyo (-present)
2013Team Leader, Quantum Nano-Scale Magnetism Research Team, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science (-present)


In Quantum Nano-Scale Magnetism Team, we fabricate nano-scale magnetic tunnel junctions and ferromagnetic/nonmagnetic hybrid nano-structures consisting of metals, semiconductors, and insulators to study quantum behaviors in domain wall displacement and magnetization dynamics mediated by spin current, i.e. a flow of spin angular momentum. In particular, we focus our investigation on the fundamental process of spin angular momentum conversion between quasi-particles such as electron spin, magnon and phonon to improve the efficiency to generate the spin current. We also aim at developing a new technique to control the spin conversion by using underlying exchange and spin-orbit interactions, and develop a new class of low power spintronic devices for innovative energy harvesting.

Research Fields

Physics, Engineering, Materials Sciences


Spin accumulation
Spin current
Spin Hall effect
Edelstein effect


Paving the way for low-power spintronics devices using material surfaces

– Efficient charge-to-spin current conversion in surface state of topological insulator –

Modern electronic devices are based on the fundamental concept of electrical charges moving through a circuit. There are, however, alternative schemes that promise faster and more efficient computing. An example is spintronics, which exploits the electrons’ magnetic properties, their spins, as well as their electronic charges. By exploiting spin current, it is possible to suppress the heat that is generated when electric current flows and instead create devices that can control and transfer information while consuming only very low power. So far, spin current has been generated and detected using the “spin Hall effect” in paramagnetic metals (metals that show magnetic properties when an external magnetic field is applied). However, the generation and detection efficiency are low, and a new conversion principle is required for the dramatic efficiency gains required for development of low-energy consumption devices. Our team has observed the high-efficiency conversion of spin current to electric current at the surface of a topological insulator. Furthermore, we found that the sign of the charge-to-spin current conversion is independent of carrier type (i.e., it doesn’t matter whether it is a negative electron or positive hole that is carrying the charge), a phenomenon unique to topological insulators and which differs from the spin Hall effect. This discovery is expected to contribute to the further development of low-power spintronics devices using material surfaces.


Yoshichika Otani

Team Leader yotani[at]riken.jp R

Kouta Kondou

Research Scientist

Bivas Rana

Postdoctoral Researcher

Junyeon Kim

Postdoctoral Researcher

Jorge Luis Puebla Nunez

Postdoctoral Researcher

Tomoyuki Yokouchi

Special Postdoctoral Researcher

Florent Auvray

Student Trainee

Hanshen Tsai

Student Trainee

MingRan Xu

Student Trainee

Heeman Kim

Student Trainee



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