Theory of spin-wave-induced electric polarization in magnetic insulators

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K21040
• Project/Area Number (Other): 18H05855 (2018)
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund (2019); Single-year Grants (2018)
• Review Section: 0202:Condensed matter physics, plasma science, nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Japan Atomic Energy Agency
• Principal Investigator: Yamamoto Kei 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 先端基礎研究センター, 研究職 (10746811)
• Project Period (FY): 2018-08-24 – 2022-03-31
• Keywords: スピン波 / 磁性薄膜

Outline of Final Research Achievements

In this research project, we studied spin waves, i.e. propagating oscillations of magnetic moments, when the magnetic medium does not possess spatial inversion symmetry. Although we were not able to complete the initially proposed study of generating electric polarisation from spin wave dynamics, we discovered several closely related phenomena and established their theoretical descriptions. Specifically, we found that when a magnetic film is attached to the surface of an electrically polar substrate, the spin waves acquire a diode-like property where they achieve practically unidirectional transmission, and they become capable of travelling spatially up to 1 mm, an improvement of orders of magnitude in comparison with bare magnetic films. These new findings might help realising information transfer devices utilising spin waves in magnetic thin films.

Free Research Field

スピントロニクス

Academic Significance and Societal Importance of the Research Achievements

スピン波は金属だけでなく絶縁体中も伝搬し、かつ磁気的な自由度であるスピンに情報を担うことができるため、情報処理技術において従来の金属や半導体を用いたエレクトロニクスでは実現できない機能を実現させるための基礎現象として注目されている。本研究成果によって明らかにされたスピン波の一方向伝搬性や長距離伝搬性は、スピン波をマイクロ波信号処理に用いるためには不可欠となる要素であり、新しい物理現象の開拓という学術的価値と将来の技術応用に向けた機能性向上の両面で意義を持つ。