Prediction of weak topological insulators in layered semiconductors

Abstract

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. Though 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.

5 pages, 4 figures

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• Experimental realization of two-dimensional weak topological insulators
• Room-Temperature Topological Phase Transition in Quasi-One-Dimensional Material Bi${}_4$I${}_4$
• Unusual Dirac fermions on the surface of noncentrosymmetric $\alpha$ - BiPd superconductor
• Towards Layer-Selective Quantum Spin Hall Channels in Weak Topological Insulator Bi4Br2I2
• Characterizing the weak topological properties: Berry phase point of view
• Dimensional evolution between one- and two-dimensional topological phases
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• Effective model for massless Dirac electrons on a surface of weak topological insulators
• Chemical Gating of a Weak Topological Insulator: Bi14Rh3I9
• Engineering Dirac electrons emergent on the surface of a topological insulator