报告题目：磁性材料中的自旋群对称性

Spin crystalline group in magnetic materials

报告人：刘奇航 副教授，南方科技大学

邀请人：王健 教授

报告时间和地点：8月3日下午2:30，致原楼1007室

摘要：The physical properties in magnetic-ordered materials was ultimately believed to rely on the symmetry theory of magnetic groups. Recently, it has come to light that a more comprehensive group, known as spin group, which combines separate spin and spatial operations, is necessary to fully characterize the geometry and underlying properties of magnetic-ordered materials such as altermagnets [1]. In this talk, we introduce the recent developments of spin group theory, including extensive enumeration of over 100000 spin space groups, identification of spin groups for collinear, coplanar, and noncoplanar configurations, and derivation of irreducible co-representations in momentum space leading to more energy degeneracies that are disallowed by magnetic groups [1,2]. We further show some theoretical and experimental results of spin group applications in understanding physical effects beyond the framework of magnetic groups. Examples include new quasiparticles in antiferromagnet CoNb3S6 [3,4], new spin splitting effects in antiferromagnets [2,5], and unconventional magnons in collinear magnets [6].

[1] Liu et al. Phys. Rev. X 12, 021016 (2022).

[2] Ren et al. arXiv:2307.10369 (2023).

[3] Liu et al. The Innovation 3, 100343 (2022).

[4] Zhang et al. arXiv:2301.12201 (2023).

[5] Zhu et al. arXiv:2303.04549 (2023).

[6] Chen et al. arXiv:2307.12366 (2023).

报告人简介：刘奇航，南方科技大学副教授，本科及博士均毕业于北京大学物理学院，曾任美国西北大学博士后、美国科罗拉多大学博尔德分校助理研究员。主要从事计算凝聚态物理研究，研究兴趣聚焦于量子材料中新奇的多自由度耦合现象，包括自旋-局域磁矩-轨道耦合作用下的对称性新理论和新效应，以及相关的新材料设计筛选 。发表SCI论文80余篇，H指数35。2018年作为独立PI后发表通讯作者文章30余篇，包括11篇PRL/PRX、4篇Nat. Commun. 、3篇Natl. Sci. Rev. 等。2020年作为项目负责人获批国家重点研发计划“量子调控与量子信息”重点专项（青年项目），2022年获批深圳市杰青项目，2021与2022年连续入选斯坦福大学发布的全球前2%顶尖科学家榜单（World’s Top 2% Scientists）。