University of Tokyo Team Develops Ultra-Fast Low-Power Switching Technology

Insider Brief

• Researchers from The University of Tokyo and RIKEN demonstrated a non-volatile switching element operating with 40-picosecond electrical pulses using the antiferromagnetic material Mn₃Sn.
• The study showed that spin-orbit torque can enable ultra-fast switching with lower heat generation and improved durability compared to conventional approaches.
• Researchers also demonstrated switching using a 60-picosecond photocurrent pulse, highlighting potential links between optical signals and non-volatile spintronic memory systems.

PRESS RELEASE — The research group, including Professor Tsai Hanshen, Special Assistant Professor Matsuda Takuya (at the time of the study), and Professor Nakatsuji Tomo of the Graduate School of Science at the University of Tokyo, is comprised of Professor Arita Ryotaro of the Graduate School of Science (and Team Director of the Center for Emergent Matter Science at the RIKEN Institute), Professor Takenaka Mitsuru of the Graduate School of Engineering, Assistant Professor Shimizu Kotaro, and Professor Iizuka Tetsuya In collaboration with Shinji Miwa, Associate Professor at the Institute of Solid State Physics, and Kota Kondo, Senior Researcher at the Center for Emergent Materials Science, RIKEN (at the time of the study) (currently Associate Professor at the Osaka University Advanced Interdisciplinary Research Organization), we used the antiferromagnetic material Mn₃Sn We have shown that magnetic states (binary values) can be rewritten, or switched, by extremely short electrical pulses of 40 picoseconds (pico is parts per trillion).

In today’s CPUs and GPUs, when processing speed increases, the energy consumed typically increases so much that it is difficult to achieve operating speeds of less than nanoseconds (nano is one part in a billion). In fact, various mechanisms have been explored to achieve picosecond switching 1,000 times faster, but challenges remain in terms of durability due to temperature increases of hundreds of degrees, and picosecond switching is still in the research and development stage for practical application.

In the antiferromagnetic device used in this study, we showed that a spin-orbit torque based on heat-independent angular momentum transfer enables picosecond switching operation that combines significant reduction in heat generation with high durability. This is the only method that is not reachable by the picosecond switching mechanisms traditionally considered.

Furthermore, we demonstrated that similar switching is also possible with a 60-picosecond photocurrent pulse generated by a combination of a telecommunication band laser and a photoelectric converter. This corresponds to a fundamental demonstration of “spintronic photoelectric conversion,” which converts an optical signal into an electrical signal and connects it directly to writing in non-volatile memory.

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