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Nano Research

Article Title

Gallium bismuth halide GaBi-X2 (X = I, Br, Cl) monolayers with distorted hexagonal framework: Novel room-temperature quantum spin Hall insulators

Keywords

quantum spin Hall (QSH) insulators, first-principles calculations, GaBi-X2 (X = I, Br, Cl) monolayers, distorted hexagonal framework, distorted Dirac cone

Abstract

ABSTRACT Quantum spin Hall (QSH) insulators with a large topologically nontrivial bulk gap are crucial for future applications of the QSH effect. Among these, group III–V monolayers and their halides, which have a chair structure (regular hexagonal framework), have been widely studied. Using first-principles calculations, we formulate a new structure model for the functionalized group III–V monolayers, which consist of rectangular GaBi-X2 (X = I, Br, Cl) monolayers with a distorted hexagonal framework (DHF). These structures have a far lower energy than the GaBi-X2 monolayers with a chair structure. Remarkably, the DHF GaBi-X2 monolayers are all QSH insulators, which exhibit sizeable nontrivial band gaps ranging from 0.17 to 0.39 eV. The band gaps can be widely tuned by applying different spin-orbit coupling strengths, resulting in a distorted Dirac cone.

Graphical Abstract

Publisher

Tsinghua University Press

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