第7回物理工学科教室談話会[Prof. Yuan-Ming Lu・2/27(木)15:00～16:30]

講　師：Prof. Yuan-Ming Lu
所　属：The Ohio State University（オハイオ州立大学）
題　目：Topological Magnons and Where to Find Them
日　時：2025 年 2 月 27 日(木)15:00～16:30
Date and Time: February 27, 2025 (Thursday) 15:00-16:30
場　所：工 6 号館 1 階大会議室
Place: Large Conference room, 1st floor, Engineering Bldg. 6

Abstract:
The discovery of topological insulators not only revealed new topological invariants encoded in many-body quantum mechanics, but also opened a new window into novel material platforms for quantum devices. With the help of ab initio density functional theory for electronic band structures, thousands of new topological electronic materials with protected surface states have been predicted. In contrast, in strongly correlated magnetic materials, density functional theory fails to reliably determine the magnetic interactions, making predictions of topology a challenging task in strongly correlated magnets. Here we present a symmetry-based approach, which predicts topological magnons in a magnetically ordered material, upon applying external perturbations such as magnetic/electric fields and/or mechanical strains. We apply this approach to carry out an efficient semi-automatic search for magnetic materials in the Bilbao Crystallographic Server (BCS). Among 198 compounds with an over 300 K transition temperature, we identify 12 magnetic insulators that support room temperature topological magnons. We further carried out a high throughput automatic search in BCS, and discovered 387 candidate materials for topological magnons, significantly expanding the pool of topological magnon materials. They provide new platforms for potential applications in topological magnon spintronics.

References:
[1] M. J. Karaki, X. Yang, A. J. Williams, M. Nawwar, V. Doan-Nguyen, J. E. Goldberger, and Y.-M. Lu, Sci. Adv. 9, eade7731 (2023).
[2] M. J. Karaki, A. E. Fahmy, A. J. Williams, S. Haravifard, J. E. Goldberger, Y.-M. Lu, arXiv:2410.18873

紹介教員：渡辺悠樹准教授（物理工学専攻）、森本高裕准教授（物理工学専攻）