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Magnetoelectric effect in band insulator–ferromagnet heterostructures

日程 : 2019年7月5日(金) 16:00 - 17:00 場所 : 物性研究所本館6階 第5セミナー室 (A615) 講師 : 岡田 健 氏 所属 : 東京大学物性研究所 世話人 : 三澤 貴宏 (ext. 63582)
e-mail: tmisawa@issp.u-tokyo.ac.jp

Electric generation and control of magnetization have been a central topic in the field of spintronics for decades. The Edelstein effect refers to a current–induced magnetization effect in noncentrosymmetric metals [1] and recently has been harnessed for magnetization control in metal-ferromagnet heterostructures [2]. Towards practical applications, however, Joule heating by a large amount of electric current could become a significant issue. In this talk, we present a theoretical study of an electric field–induced magnetization in band insulators, which is free from Joule heating by definition [3]. We reveal that this magnetoelectric (ME) effect could appear in common situations when band insulators are employed in a heterostructure with a ferromagnet. We calculate the ME tensor on a simple model of a generic two-dimensional band insulator attached to a ferromagnet by the linear-response theory. In this model, the electrons in the band insulator are subject to the Rashba spin-orbit coupling due to the heterointerface as well as the exchange coupling with the magnetic moment in the ferromagnet. We reveal that the ME effect generally appears without specific parameter tunings. Lastly, as a specific example, we estimate the magnitude of the ME effect in the case of a hybrid halide perovskite semiconductor and discuss its characteristics and novelty by comparison with other types of ME effect in metals or multiferroic insulators.
[1] V. M. Edelstein, Solid State Commun. 73, 233 (1990).
[2] I. M. Miron et al., Nat. Mater. 9, 230 (2010).
[3] K. N. Okada, Y. Kato, and Y. Motome, PRB 99, 134442 (2019).

(公開日: 2019年06月17日)