【学术活动预告】Efficient Topological Materials Discovery Using Symmetry Indicators

发布时间:2018-08-25 南师物理学院 浏览次数:


报告人:万贤纲

        南京大学物理学院教授

        国家杰出青年科学基金获得者

        教育部长江学者特聘教授

报告时间:
2018 829 日(周三)下午4:00-5:00

地点:行健楼
436 会议室

邀请单位:物理科学与技术学院
量子输运与热能科学中心

 
报告人简介:

万贤纲,南京大学物理学院教授,1990年至2000年在南京大学学习,获得学士、硕士、博士学位。2001起在南京大学历任讲师,副教授,2010年任教授。主要学术成绩为:提出了新型拓扑量子态—Weyl 半金属,引发了国际上Weyl 半金属的研究热潮;发展了一套计算磁性相互作用的方法并确定多个复杂体系的基态磁构型;参与发展了symmetry indicators方法,并用其对所有非磁材料拓扑性质进行了判断。 获得2014年度香港大学Daniel Tsui Fellowship2015年获得国家杰出青年科学基金;2016年被评为教育部长江学者特聘教授。

 
报告摘要:

Abstract: Topological materials (TMs) showcase intriguing physical properties defying expectations based on conventional materials, and hold promise for the development of devices with new functionalities. While several theoretically proposed TMs have been experimentally confirmed, extensive experimental exploration of topological properties as well as applications in realistic devices have been held back due to the lack of excellent TMs in which interference from trivial Fermi surface states is minimized. Here, we integrate the recently established theory of symmetry indicators of band topology into first-principle band-structure calculations, and test it on a databases of previously synthesized crystals. The combined algorithm is found to efficiently unearth topological materials and predict topological properties like protected surface states. By applying our method to all non-magnetic compounds in the 230 space groups. An exhaustive database search reveals thousands of TM candidates. Of these, we highlight the excellent TMs, the 258 topological insulators and 165 topological crystalline insulators which have either noticeable full band gap or a considerable direct gap together with small trivial Fermi pockets. We also give a list of 489 topological semimetals with the band crossing points located near the Fermi level. All predictions obtained through standard generalized gradient approximation (GGA) calculations were cross-checked with the modified Becke-Johnson (MBJ) potential calculations, appropriate for narrow gap materials. With the electronic and optical behavior around the Fermi level dominated by the topologically non-trivial bands, these newly found TMs candidates open wide possibilities for realizing the promise of TMs in next-generation electronic devices.