（9月23日）杨鲁懿 副教授：Magnetic order induced chiral phonons and altermagnetic Kerr effect

理学部青年学者系列讲座第十五期

报告人:

杨鲁懿 副教授（清华大学）

题目:  

Magnetic order induced chiral phonons and altermagnetic Kerr effect

时间: 

2026年9月23日10:00

地点: 

哲生堂307讲学厅

主持人： 

陈祥 副教授

报告摘要：In the first part, I will report the discovery of chiral phonon modes in the kagome ferromagnetic Weyl semimetal Co3Sn2S2, a material that preserves inversion symmetry but breaks time-reversal symmetry. Using helicity-resolved magneto-Raman spectroscopy, we observe the spontaneous splitting of the doubly degenerate in-plane Eg modes into two distinct chiral phonon modes of opposite helicity when the sample is zero-field cooled below the Curie temperature, in the absence of an external magnetic field. Our findings highlight the role of the magnetic order in inducing chiral phonons, paving the way for novel methods to manipulate chiral phonons through magnetization and vice versa. 

In the second part, I will discuss our recent findings on the magneto-optical properties of hematite (α-Fe2O3), a candidate for altermagnetism. We have observed significant magneto-optical Kerr effect (MOKE) signals at room temperature, which are associated with the Neel vector. Furthermore, our research demonstrates that these pronounced MOKE effects facilitate optical imaging of altermagnetic domains and enable the study of their reversible domain wall motion. These findings suggest that MOKE can serve as a tool for identifying potential altermagnetic materials, potentially broadening the existing research landscape in the field of altermagnetism.

个人简介：

杨鲁懿2007年获清华大学学士，2013年获美国加州大学伯克利分校博士。2013-2016年在美国强磁场国家实验室从事博士后研究（LANL Director’s Postdoctoral Fellow）。2016-2019年加拿大多伦多大学任助理教授，获得Canada Research Chair、CIFAR Azeieli Global Scholar等荣誉。2019年入选青年千人并任清华大学物理系副教授。

她的专长是发展和应用先进的光谱学技术，以超高的时间和空间分辨率探测凝聚态物质系统中的超快动力学。回清华的6年内，作为独立PI，她的课题组自主研发了多个量子材料精密光学测量平台，可以同时实现低温、强磁场、高时间分辨和高空间分辨等多种极端条件的测量。利用这些平台，她的课题组在磁性拓扑材料、钙钛矿光伏材料以及氧化物功能材料的光学性质和超快动力学等方面取得一系列进展。