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物理学院“格致·创新”论坛第三十一期——吴镝教授

【来源:物理学院 | 发布日期:2018-10-12 | 作者:null 】     【选择字号:

应物理学院与萃英学院的邀请,南京大学物理学院吴镝教授来访并做客物理学院“格致﹒创新”论坛第三十一期,欢迎广大师生届时参加!

题目:Spin-orbit magnetoresistance and pure spin current detection in conductive films on magnetic insulators

时间:2018年10月19日(星期五)上午9:30

地点:格致楼3016报告厅

摘要:A magnetoresistance effect induced by the Rashba spin-orbit interaction was predicted, but not yet observed, in bilayers consisting of normal metal and ferromagnetic insulator. Here, we present an experimental observation of this new type of spin-orbit magnetoresistance (SOMR) effect in a bilayer structure Cu[Pt]/Y3Fe5O12 (YIG), where the Cu/YIG interface is decorated with nanosize Pt islands. This new MR is apparently not caused by the bulk spin-orbit interaction because of the negligible spin-orbit interaction in Cu and the discontinuity of the Pt islands. This SOMR disappears when the Pt islands are absent or located away from the Cu/YIG interface, therefore we can unambiguously ascribe it to the Rashba spin-orbit interaction at the interface enhanced by the Pt decoration. The numerical Boltzmann simulations are consistent with the experimental SOMR results in the angular dependence of magnetic field and the Cu thickness dependence. Our finding demonstrates the realization of the spin manipulation by interface engineering. In second part of my talk, I will discuss the physical origin of a dc voltage generation in a bilayer of a conducting polymer film and a micrometer-thick magnetic insulator YIG film under the ferromagnetic resonance and/or spin-wave excitation condition. The previous attributed mechanism, the inverse spin Hall effect (ISHE) in the polymer [Nat. Mater. 12, 622 (2013)], is excluded by systematically study. We found an in-plane temperature gradient in YIG which has the same angular dependence with the generated voltage. Both vanish when the YIG thickness is reduced to a few nanometers. We argue that the dc voltage is governed by the Seebeck effect in the polymer, where the temperature gradient is created by the nonreciprocal magnetostatic surface spin wave propagation in YIG.

个人简介:吴镝,教授。分别于1997年和2001年在复旦大学物理学系获学士和博士学位,研究生期间曾到香港科技大学和德国Max-Plank微结构物理研究所短期访问。博士毕业后分别在美国犹他大学和加州大学河滨分校物理系先后从事博士后和助理专家研究。自2007年到南京大学工作。主要开展自旋电子学的研究。2004年获美国犹他大学“杰出博士后奖”,2008年获得教育部“新世纪优秀人才支持计划”,2013年受聘为唐仲英特聘教授。2012年获国家自然科学基金优秀青年科学基金。