Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 14: Topological Insulators 2 (jointly with DS, HL, MA, TT)
O 14.4: Talk
Monday, March 11, 2013, 16:15–16:30, H10
Prediction of weak topological insulators in layered semiconductors — •Binghai Yan1,2, Lukas Müchler1,2, and Claudia Felser1,2 — 1Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden — 2Institute for Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz, 55099 Mainz
We report the discovery of weak topological insulators by ab initio calculations in a honeycomb lattice. We propose a structure with an odd number of layers in the primitive unit cell as a prerequisite for forming weak topological insulators. Here, the single-layered KHgSb is the most suitable candidate for its large bulk energy gap of 0.24 eV. Its side surface hosts metallic surface states, forming two anisotropic Dirac cones. Although the stacking of even-layered structures leads to trivial insulators, the structures can host a quantum spin Hall layer with a large bulk gap, if an additional single layer exists as a stacking fault in the crystal. The reported honeycomb compounds can serve as prototypes to aid in the finding of new weak topological insulators in layered small-gap semiconductors.