题目：electrical and optical detection of the multipolar structure in the magnetization space

报告人：侯达之 教授（中国科学技术大学微尺度物质科学国家研究中心）

时 间：2024年12月13日9:00~12:00

地 点：物理实验中心229会议室

摘要： The anomalous Hall effect (AHE) in ferromagnetic materials has traditionally been understood to originate from a dipolar magnetization, with the effect typically showing sensitivity to out-of-plane magnetization. In contrast, we present compelling evidence that the AHE fundamentally arises from multipolar contributions to the magnetization. This discovery enables the observation of AHE under in-plane magnetization in cubic ferromagnets such as iron and nickel, challenging the conventional view. The magnitudes of these multipoles align with the oretical predictions from our recently proposed multipolar structure of Berry curvature in magnetization space. Notably, the octupole term can dominate the AHE in certain conditions, as observed in a van der Waals ferromagnet.Furthermore, we introduce a novel MOKE geometry that detects both the magnitude and direction of the perpendicular magnetization component, enabled by the multipolar structure of Berry curvature. This orthogonal MOKE geometry reveals unique angle-dependent behaviors, providing a direct probe of the magnetization multipoles at optical frequency. Our findings offer new insights into the quantum geometry of magnetization and open new avenues for probing magnetic orders across both electrical and optical domains, offering a unified framework for the study of multipolar magnetization in the context of Berry curvature.

简历：侯达之，中国科学技术大学微尺度物质科学国家研究中心特任教授，2019年10月入职2021年1月入选第16批国家创新人才计划青年项目2021年选国家创新人才计划青年项目。主要从事凝聚态材料中的自旋相关物理现象的研究与探索、自旋相关电磁热输运性质测量。主要包括：自旋电子学新现象探索与发现、低维磁性材料新型器件研发、基于锁相红外的热成像测量。目前在国际重要学术期刊上已发表论文共34篇，其中第一作者或通讯作者文章10篇，包括Nature Materials 1篇， Physical Review Letters 3篇，Nature Communications 2篇，ASC nano 1篇，NPG Asia Materials综述论文1篇，总引用数1380次（Google Scholar）。同时担任Nature Physics, Nature Communications，Physical Review Letters，Advanced Materials等重要杂志审稿人。

联系方式：13671577535

邀请人： 周家东

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承办单位：物理学院、先进光电量子结构设计与测量教育部重点实验室