主讲人：南方科技大学 李军学 助理教授                   

题   目：Spin current generation and detection in ferrimagnetic and antiferromagnetic insulators

日   期：2021年11月2日     时   间：10:00-11:30

地   点：哈尔滨工业大学（深圳）A507

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报告人简介：

李军学博士于2015在复旦大学物理系取得凝聚态物理博士学位，2015年3月至2020年9月期间，他在加州大学河滨分校物理与天文系从事博士后研究。他于2020年12月作为助理教授加盟南科大物理系，并于2021年3月获得深圳市“国家级领军人才”称号。李军学博士的主要研究兴趣集中于探索纳米尺度电子器件与异质结中的新奇物理现象，这些现象一般起源于物质内部或者器件界面的复杂相互作用；另一方面，对于新兴的量子材料和磁性材料，他对于利用分子束外延和脉冲激光沉积技术生长单晶外延薄膜也非常感兴趣。李军学博士共发表学术论文30篇，其中以第一作者及共同一作身份发表论文9篇，包括Nature (1篇)，Nature Communications (1篇)，Phy. Rev. Lett. (2篇)，Nano Lett. (1篇)，Phy. Rev. B (2 篇)等。截止目前，其谷歌学术引用为911次，H因子为19。

摘   要：Spin current represents a flow of spin angular momentum and does not require movement of charges. Magnetic insulators, including ferro-, ferri-, and antiferro-magnetic insulators, can therefore work as a source as well as a transport medium of spin currents. The advantages of these materials include low magnetic damping, long magnon diffusion length, and high ordering temperature. Here, I will present our recent progresses in generation and detection of spin currents using ferrimagnetic insulator Y3Fe5O12 (YIG) and antiferromagnetic (AFM) insulator Cr2O3. First, we demonstrate the electrical injection and detection of spin current in heavy metal (HM)/YIG/HM heterostructures, which can be used as an effective spin current valve [1]. Secondly, we successfully pump pure spin current out from AFM insulator Cr2O3 using sub-THz microwave and detect it electrically [2]. Both coherent and incoherent AFM magnons are found to contribute to the spin current. Last, the hybridization between magnon and phonon in AFM insulator Cr2O3 is systematically investigated via spin Seebeck effect [3]. These findings open up many exciting possibilities of potential spintronics applications of magnetic insulators.

[1] J. X. Li#, et al., Nat. Commun. 7, 10858 (2016).

[2] J. X. Li, et al., Nature (London) 578, 70 (2020).

[3] J. X. Li, et al., Phys. Rev. Lett. 125, 217201 (2020).