AMS 日本語

INTRODUCTION OF LABORATORY

Otani group has been carrying out spintronics research since 2004. The group has developed static and dynamic electrical generation and detection techniques of the spin angular momentum flow, called spin current, the fundamental physical entity responsible for various spintronics phenomena such as a nonlocal spin valve, spin-transfer torque, spin-orbit torque, Edelstein effects, and spin Hall effects. The group's research interests have evolved into the development and elucidation of various novel spin-mediated conversion phenomena among quasiparticles such as electrons, magnons, phonons, and photons. These interconversion phenomena mentioned above arise from spin-orbit interaction inside, on surfaces, and at interfaces of solids. The group has demonstrated a significant Rashba Edelstein effect at the interface of various metal-oxide interfaces. The group has also recently discovered a new class of spin Hall effects, i.e., magnetic spin Hall effects in quantum materials, Mn3X (X=Sn and Ge) in collaboration with colleagues in the quantum materials group. The magnon-phonon coupling is also an important research topic in the group. The group has established the acoustic spin pumping method to inject an acoustic wave into ferromagnetic thin films. This method enabled the group to study the Magneto-rotation coupling, which is fundamentally different from the magneto-elastic coupling. Thereby, the group has succeeded in observing the 100 % rectification of surface acoustic waves propagating in an ultra-thin ferromagnetic thin film. The group has also demonstrated the manipulation of Skyrmion creation and annihilation by using surface acoustic waves. The final goal of the group is the realization and understanding of new spin-mediated coupling among various quasiparticles.

　

Magnetic spin Hall effect in a non-collinear antiferromagnet: discovery of a magnetic contribution to the spin Hall effect. (a) Schematic of the spin-accumulation device: Ferromagnetic and non-magnetic electrodes contact a top surface of a microfabricated Mn₃Sn. (b) The magnetic inverse spin Hall effect originates the spin-accumulation signal. Opposite signs of the hysteresis appear after reversing the spins of Mn,₃Sn. The corresponding spin structures of Mn,₃Sn are shown in the inset.

　

The spin-charge current conversion at the molecule/metal interface was observed by employing the spin pumping method. (a) The schematics of the PbPc/Cu interface and the spin pumping measurement. (b) Spin pumping induced voltage signal originated in the spin-charge current conversion. (c) Scanning tunneling microscopy image of a single layer PbPc film on Cu(111).

PROFILE

Professor Yoshichika Otani

Prof. YoshiChika Otani received the B.S., M.S., and Ph.D. degrees from Keio University, Japan, in 1984, 1986, and 1989. He was a research fellow at the Physics Department of Trinity College Dublin, the University of Dublin, Ireland (1989–1991), and a researcher at the Laboratoire Louis Néel, CNRS, France (1991–1992). He was an assistant professor at the Department of Physics, Keio University (1992–1995) and an associate professor at the Department of Materials Science, Tohoku University (1995–2002). From 2001 to 2012, Prof. Otani led, as a team leader, the Quantum Nano-Scale Magnetics Research Team at the RIKEN Frontier Research System (FRS). In 2004 he became a professor at the Institute for Solid State Physics (ISSP), the University of Tokyo. Since 2013, Prof. Otani has also been the Quantum Nano-Scale Magnetism Research Team leader at the RIKEN Center for Emergent Matter Science (CEMS). He has been working on experimental spintronics, studying spin current-related physics in nanoscale devices consisting of magnetic and non-magnetic materials, including topological insulators, chiral antiferromagnets, and chiral molecules.

STUDENT VOICE

Ayuko Kobayashi

Prof. Otani possesses an in-depth understanding of physics, thus he naturally serves as a role model for students. He not only inspires students and values their opinions on their desired paths, but also leads them with clear guidance that prioritizes outstanding results. Students are expected to proactively give presentations at international conferences and join collaborative research with overseas institutions, which is supported by our day-to-day discussions with many non-Japanese researchers. With these experiences, many students have chosen to follow carrier paths outside of Japan after graduation. The laboratory members share a strong common purpose in solving challenging problems in modern society, dedicating ourselves as a team.