Prof Ono(left) and Prof Saitoh(right)
This year the prize selection committee decided there were two people worthy of being awarded the Sir Martin Wood Prize. The two winners are Prof. Teruo Ono from Kyoto University and Prof Saitoh from Keio University, who has recently moved to the Institute for Materials Research at Tohoku University.
Summary of achievements :
Professor Ono demonstrated the control of magnetization in nano-magnets (magnetic wire or magnetic disk) by electric current without using a magnetic field. The current-driven domain wall (DW)motion is considered as a kind of magnetic excitation by a current which flows through a spin structure with spacial variation. This concept has been tested for another typical noncollinear spin structure, a magnetix vortex. He has found that the direction of a vortex core can be switched by ac current or by a single nano-second current pulse. The electrical control of magnetization described here is very efficient and scalable down to nano-world because it is based on the quantum mechanical interaction between the flowing spins and the localized spins that constitute magnetization, and thus it will be a key technology for future spintronic devices. In fact, IBM proposed the novel storage device called “race-track memory”, whose operation relies on the current-driven DW motion. The current-induced vortex core switching can be used as an efficient data writing method for a memory device in which the data are stored in a nanometer size core.
Professor Saitoh reported the discovery of novel phenomena associated with spin currents. These include:
(1) Inverse spin-Hall effect: A flow of a spin current generates voltage and an electric field, a phenomenon which allows the electric detection of a spin current. This is reminiscent of Ampere’s law, in which an electric current generates a magnetic field, but the inverse spin-Hall effect is enhanced typically in metals which exhibit strong spin-orbit interaction, such as in Pt.
(2) Spin-Seebeck effect: A temperature gradient generates spin voltage, or driving force for spin currents. This effect allows to extract spins from every position on magnets simply by attaching a metal.
These findings should revolutionize basic research on spin currents and lead to dramatic advances in spintronics.
Prof Ono and Prof Saitoh will be spending a week in the UK to present their work in various British universities:
- Tuesday 23rd June, Oxford University.
- Wednesday 24th June, York University
- Thrusday 25th June, University College London(UCL)
- Friday 26th of June, Cambridge University.