4D Topological Insulators with Nodal-Line Boundary States

报告题目：4D Topological Insulators with Nodal-Line Boundary States

报告人:赵宇心  南京大学

报告时间：12月11日 下午 16:00-17:00

报告地点：物理科技楼101

报告邀请人： 江华

报告摘要：Conventional topological insulators and superconductors have topologically protected nodal points in their boundaries, and the recent interests in nodal-line semimetals merely concerned bulk band structures. In this talk, we present a novel four-dimensional topological insulator protected by an anti-unitary refection symmetry, whose boundary band has a single PT-symmetric nodal line with double topological charges. The construction of the model is guided by the K-theoretical formulation of the bulk-boundary correspondence of topological insulators. Fascinatingly, the Z2 bulk topological invariant is formulated as the second Chern number over a half Brilliance zone subtracted by Chern-Simons integrals over its boundaries, and therefore can be regarded as a four-dimensional generalization of the topological invariant of 2D time-reversal-invariant topological insulators. A cold-atom realization proposal will also be briefly discussed.

[1]L. B. Shao and Y. X. Zhao, arXiv:1805.07323.

[2]Y. X. Zhao, A. P. Schnyder and Z. D. Wang, Phys. Rev. Lett. 116, 156402 (2016).

[3] Y. X. Zhao, Y. Lu, Phys. Rev. Lett. 118, 056401 (2017).

报告人简介：2010年在北京大学物理系取得学士学位，2014年在香港大学物理系取得博士学位。之后，在德国马普固体物理所理论部做博士后研究，并于2017年在香港大学物理系做研究助理教授。获得第十三届千人计划青年项目后，在2017年9月回到南京大学物理学院担任教授。主要从事凝聚态理论中拓扑相相关的研究。