Quantum spin Hall effect and topological phase transition in two-dimensional square transition-metal dichalcogenides

Ma, Yandong, Kou, Liangzhi, Li, Xiao, Dai, Ying, Smith, Sean C., & Heine, Thomas (2015) Quantum spin Hall effect and topological phase transition in two-dimensional square transition-metal dichalcogenides. Physical Review B - Condensed Matter and Materials Physics, 92(8), 085427.

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Two-dimensional (2D) topological insulators (TIs) hold promise for applications in spintronics based on the fact that the propagation direction of an edge electronic state of a 2D TI is locked to its spin orientation. Here, using first-principles calculations, we predict a family of robust 2D TIs in monolayer square transition-metal dichalcogenides MX2(M=Mo,W;X=S,Se,Te), which show sizeable intrinsic nontrivial band gaps ranged from 24 to 187 meV, thus ensuring the quantum spin Hall (QSH) effect at room temperature. Different from the most known 2D TIs with comparable band gaps, these sizeable energy gaps arise from the strong spin-orbit interaction related to d electrons of the Mo/W atoms. A pair of topologically protected helical edge states emerges at the edge of these systems with a Dirac-type dispersion within the bulk band gap. The topologically nontrivial natures are confirmed by the nontrivial Z2-type topological invariant. More interestingly, with applied strain, a topological quantum phase transition between a QSH phase and a trivial insulating/metallic phase can be realized, and the corresponding topological phase diagram is well established. © 2015 American Physical Society.

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ID Code: 98200
Item Type: Journal Article
Refereed: Yes
DOI: 10.1103/PhysRevB.92.085427
ISSN: 2469-9950
Copyright Owner: Copyright 2015 American Physical Society
Deposited On: 18 Aug 2016 05:24
Last Modified: 18 Aug 2016 23:51

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