Active controll of the magnetization damping by electric field effect in magnetic metal

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15437
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: Nihon University
• Principal Investigator: KASATANI Yuichi 日本大学, 理工学部, 研究員 (30836507)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 磁化緩和機構 / ダンピング定数 / 強磁性共鳴 / 磁気光学効果 / 電界効果 / 異常ネルンスト効果

Outline of Final Research Achievements

The goal of this study is active control of the magnetization relaxation mechanism by external parameters such as voltage. The measurement system and the sputtering machine were newly set up. Distinct change of the magnetization relaxation mechanism was not observed with applying the voltage. It is suggested that sample structure and voltage intensity are important to control the damping constant. Since it was difficult to prepare new samples due to the breakdown of the sputtering machine, I have changed original plan and investigated the thermomagnetic effect in rare earth-transition metal ferrimagnetic alloys. By applying a temperature gradient to the Gd-Fe alloy ferrimagnetic thin film, I found that anomalous Nernst effects occur in wide range of composition ratio. I also qualitatively found that the magnitude and polarity of the anomalous Nernst voltage changes sensitively in response to the dominant sublattice elements with changing the composition ratio.

Free Research Field

スピントロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた成果の学術的意義は、時間領域と周波数領域の両方の観点から磁化緩和機構を複合的に捉え、変化中の過渡状態と結果としてのパラメータ変化から電子状態と磁化緩和機構の関係に深くアプローチすることを可能にした。また、広範な合金組成の希土類―遷移金属合金フェリ磁性体で異常ネルンスト効果が生じ、その大きさや極性の組成・温度依存性を示した。社会的意義としては、磁化緩和機構の能動的制御指針を示すことでデバイス応用への可能性を見出した。さらに、近年注目されている熱磁気効果をデバイス応用する上で、希土類―遷移金属フェリ磁性体を用いることによって比較的容易な特性制御の可能性を示したと言える。