主讲人：张先鹏 博士（香港科技大学）

题目：Spin transport in heavy metal/magnetic insulator heterostructures

时间：2024年3月30日（周六）上午10：00

地 点：理工楼1226

联系人：贾成龙

报告摘要：

Spintronics aims to enhance the capabilities of conventional electronics by utilizing the interconversion of spin angular momentum between different carriers in solid-state materials. One crucial aspect of spintronics is the exchange of spin between conduction electrons in non-magnetic metals and the magnetization in ferromagnetic materials, which plays a central role in manipulating magnetization for the development of innovative magnetic memory devices. The focus of this talk is to present various spin-dependent phenomena observed in heterostructures of heavy metal (HM) and magnetic insulator (MI). Firstly, we introduce our microscopic theory of spin Hall magnetoresistance (SMR) in HM/MI heterostructures [1]. We express the spin mixing conductances, which govern the phenomenology of SMR, in terms of interface microscopic parameters and the spin-spin correlation functions of local moments on the MI surface. Furthermore, we present experimental demonstrations of our theory in both paramagnetic [2] and ferromagnetic [3] scenarios. It is noteworthy that heavy metals themselves exhibit significant spin-orbit coupling, and the breaking of inversion symmetry at the HM-MI interface induces a strong spin-orbit coupling effect. Lastly, we develop a microscopic theory based on SU(2) gauge field theory to explain spin-orbit torque and spin memory loss resulting from interfacial spin-orbit coupling [4]. This theoretical framework allows us to understand the underlying mechanisms behind these phenomena and provides insights into the design and optimization of spintronic devices.

个人简介：

Dr. Zhang Xianpeng is primarily engaged in theoretical condensed matter physics, with a specific focus on spintronics and superconductivity. His research interests encompass quantum transport, quantum magnetism, and superconductivity, among others. Dr. Zhang completed his bachelor's degree at Fuzhou University, followed by master's degrees at National Tsing Hua University in China,Taiwan, and ultimately obtained his Ph.D. from the University of the Basque Country in Spain in late 2020. During his Ph.D., he was supervised by Prof. Sebastian Bergeret and Prof. Miguel Cazalilla. Following his doctoral studies, Dr. Zhang pursued a postdoctoral position in the group of Prof. Daniel Loss at the University of Basel in Switzerland. Currently, he holds a postdoctoral position in the research group led by Professor Liu Junwei at the Hong Kong University of Science and Technology.