韩国基础科学研究所 博士
腾讯会议：159-754-897
会议密码：0817
会议链接：https://meeting.tencent.com/dm/UU0USSsXNTMy
报告摘要：
Surface states are the fingerprint of topological materials due to the anomalous characteristics that are unachievable in ordinary periodic systems. Especially, in magnetic crystals, there is great potential to achieve new distinct anomalous surface states. Firstly, I will introduce a new type of magnetic TCI, coined the topological magnetic Dirac insulator (TMDI), whose two-dimensional (2D) surface hosts fourfold-degenerate Dirac fermions protected by either the p'c4mm or p4'g'm magnetic wallpaper group. The bulk band topology of TMDIs is protected by diagonal mirror symmetries, which give chiral dispersion of surface Dirac fermions and mirror-protected hinge modes. A class of candidate materials for TMDIs, including Nd4Te8Cl4O20 and DyB4, will be also introduced. Second, I will introduce another interesting ferromagnetic topological semimetal CoS2, which possesses a new type of topological surface state, dubbed floating surface state (FSS). The fundamental origin of the dominant FSSs in CoS2 is unveiled: obstructed atomic band topology and broken crystal field, spreading over the entire surface Brillouin zone independent of surface orientation. Moreover, the surface states from topological nodes just mildly modulate the surface band connection while global surface state structure is governed by the FSS. The two types of FSSs have the opposite spin polarizations and their relative weight varies depending on the termination surface, which allows to control the surface spin polarization through surface manipulation.
Refs:
[1]“Magnetic wallpaper Dirac fermions and topological magnetic Dirac insulators”, Hwang Y, Qian Y, et al, npj Computational Materials 9, no. 1 (2023): 65.
[2]“Floating spin-polarized surface states of pyrite ferromagnetic topological semimetal CoS2”, Qian Y et al, submitted.
报告人简介：
钱玉婷，2021年在中国科学院物理研究所获得博士学位，2021年至今于韩国基础科学研究所相关电子系统中心（IBS-CCES，首尔国立大学）从事博士后研究。主要从事拓扑材料物性研究的第一性原理计算，在拓扑半金属、拓扑绝缘体、拓扑晶体绝缘体等电子系统和拓扑声子系统的研究方面发表SCI论文20余篇。目前主要兴趣是新型磁性拓扑材料的寻找和磁性拓扑物态的理论计算。
邀 请 人：吴泉生 特聘研究员
联 系 人：王慧颖 why@iphy.ac.cn