2017/06/30
Keio University
National Institute for Materials Science
A research group led by Koji Sekiguchi, a full-time lecturer at the Department of Physics, Faculty of Science and Technology, Keio University, and Hiroaki Sukegawa, a principal investigator at the National Institute for Materials Science, has succeeded in propagating magnetic waves (spin waves) without using electromagnets by using extremely high-quality magnetic metal crystals. This has improved the spin-wave generation efficiency by 400% and the propagation speed by up to 80%. This marks a step forward in solving the integration challenges that have hindered the practical application of spin-wave logic devices.
Logic devices that make up the central processing unit (CPU), the heart of information processing equipment, operate by switching the electric current on and off, which means moving or not moving electrons. This conventional electron-moving method generates significant heat, and the limits of integration and high-speed operation are approaching. On the other hand, using spin waves instead of electrons allows signals to be transmitted without generating heat in principle, as they are "waves" that propagate the rotational motion of spins. Therefore, it is expected that "magnon transistors" based on an energy-saving operating principle that can drastically improve energy efficiency will become possible.
Much research and development has been conducted to realize "magnon transistors." Although the operational principle has been experimentally verified, generating spin waves (magnons) for computation required a large current to be passed through the device wiring, which was not an energy-efficient method when considered overall. Furthermore, the need for electromagnets made integration extremely difficult, and to date, only large, millimeter-sized devices have been created.
This study demonstrates for the first time that logic operations can be performed with spin waves without using electromagnets. This was achieved by utilizing the magnetic anisotropy of magnetic single crystals, where properties differ depending on the crystal orientation, to create regions with and without spin waves within a single crystal sample. This result, which shows that logic operations are possible using only anisotropic crystals, opens the way for integration. Furthermore, because of the extremely high-quality metal crystals, the spin-wave generation efficiency improved by 400%, and the propagation speed increased by up to 80%.
With these achievements in new spin-wave control technology, high-efficiency spin-wave generation, and high-speed spin-wave propagation, it is expected that "magnon transistors" will develop as a new cornerstone for realizing dramatic performance improvements and energy savings in computers and other electronic devices.
This research result will be published in the online advance publication of "NPG Asia Materials," a specialized journal of the British scientific journal Nature, on June 30, 2017 (UK time).
For the full press release, please see below.