Large gap two dimensional topological insulators: bilayer triangular lattice TlM (M = N, P, As, Sb)

P. Zhou; L. Xue; L. Z. Sun

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arXiv · 1612.08889

Large gap two dimensional topological insulators: bilayer triangular lattice TlM (M = N, P, As, Sb)

P. Zhou·L. Xue·L. Z. Sun

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Abstract

Based on density functional theory and Berry curvature calculations, we predict that p-p band inversion type quantum spin Hall effect (QSHE) can be realized in a series of two dimensional (2D) bilayer honeycomb TlM (M = N, P, As, Sb), which can be effectively equivalent to bilayer triangular lattice for low energy electrons. Further topological analysis reveals that the band inversion between pz- and px,y of M atom contributes to the nontrivial topological nature of TlM. The band inversion is independent of spin-orbit coupling which is distinctive from conventional topological insulators (TIs). A tight binding model based on triangle lattice is constructed to describe the QSH states in the systems. Besides the interesting 2D triangular lattice $p-p$ type inversion for the topological mechanism, the maximal local band gap of the systems can reach 550 meV (TlSb), which provides a new choice for future room temperature quantum spin Hall Insulator (QSHI). Considering the advance of the technology of van der Waals passivation, combining with hexagonal materials, such as h-BN, TlMs show great potential for future 2D topological electronic devices.

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P. Zhou, L. Xue, L. Z. Sun. 2016-12-28. Large gap two dimensional topological insulators: bilayer triangular lattice TlM (M = N, P, As, Sb). https://arxiv.org/abs/1612.08889

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