报告人：高阳，教授 (中科大)

时 间：2023年3月23日(周四)晚上 18:30

地 点：腾讯会议， 会议号： 347-109-020

摘要：

反铁磁体由于其对外磁场不敏感以及其太赫兹频域的动力学行为等性质广受关注，有望成为新一代超快自旋电子器件的核心单元。为达到此目标，人们需要对反铁磁序进行有效的探测与操控。通过线偏光二向色性（linear dichroism）和各向异性磁电阻（AMR），我们可以方便的看到反铁磁序的空间转动。然而二者无法分辨反铁磁序的翻转。在此报告中，我们考察了两种非线性非互易现象：内禀非线性霍尔效应与线偏光的方向二向色性。它们都对时间反演敏感而对联合时空反演不敏感，故非常适合于探测反铁磁序的翻转。我们将分析这两种现象的微观几何起源，为其进一步的优化与调控提供思路。

简历：

高阳，2009年本科毕业于北京大学，2016年在美国德州大学奥斯汀分校获得博士学位，后在卡耐基梅隆大学做博士后。2020年加入中国科学技术大学best365平台。科研着重于通过非线性输运与非线性光学效应理解凝聚态物质中准粒子的几何与拓扑性质和晶格、自旋以及各种序参量间的复杂的相互作用。

联系方式：junxi.duan@bit.edu.cn

邀请人：段俊熙

网 址：http:/

承办单位：best365平台、先进光电量子结构设计与测量教育部重点实验室

*Reporter：Prof. Yang Gao (USTC)

*Time：2023-03-23 (Thursday) 18:30

*Place： Online talk in Tencent Meeting: 347-109-020

*Contact Person: Junxi Duan

*Abstract:

Due to the robustness against external magnetic fields and ultrafast dynamics, antiferromagnets are essential for next-generation spintronic devices. To achieve this goal, the antiferromagnetic order needs to be detected and manipulated efficiently. Through the linear dichroism and anisotropic magnetoresistance, the spatial orientation of the antiferromagnetic order can be probed. However, both methods are insensitive to the reversal of the antiferromagnetic order. In this talk, we consider two types of nonlinear nonreciprocal effects: the intrinsic nonlinear Hall effect and the nonreciprocal directional dichroism. Both of them are sensitive to the time reversal symmetry but insensitive to the combined TI symmetry. Therefore, they can be used to probe the reversal of the antiferromagnetic order. Further analysis shows that they are deeply related to the quantum metric and Berry curvature, suggesting intimate connection between the macroscopic antiferromagnetic order and microscopic geometrical properties. This connection offers efficient tuning methods through the Berry curvature/quantum metric engineering.

*Profile：

Dr. Yang Gao received his bachelor degree from Peking University, and doctorate from University of Texas at Austin. He then worked as a postdoc at Carnegie Mellon University. He joined USTC since 2020. His research interest is unraveling the intertwined relation between the topological and geometrical properties, and various degrees of freedom such as charge, valley, spin, and lattice, through nonlinear transport and nonlinear optical phenomena.