First-principles study of the nonsymmorphic Dirac insulator

Recently, we have found a novel topological crystalline insulator phase, referred to as the nonsymmorphic Dirac Insulator [1]. Unlike the time-reversal Z2 topological insulator, the nonsymmorphic Dirac insulator is a characterized by a single four-fold degenerate Dirac point, occurring on the p4g or pgg invariant surface of the otherwise band insulator. Inthis talk, we will present our first-principles study to find the material realization of the nonsymmorphic Dirac insulator. After introducing a general scheme to calculate the Z4XZ2 topological invariants using the symmetry-labeled Wilson loop calculations, we show Sr2Pb3 can host the (2,2) phase, hosting a single four-fold degenerate Dirac on the (001) surface.

[1] Wieder, Benjamin J., Barry Bradlyn, Zhijun Wang, Jennifer Cano, Youngkuk Kim, Hyeong-Seok D. Kim, A. M. Rappe, C. L. Kane, and B. Andrei Bernevig. "Wallpaper Fermions and the Topological Dirac Insulator." arXiv preprint arXiv:1705.01617 (2017).