2015/04/01 by Yandong Ma, Liangzhi Kou, Xiao Li +3 · 141 citations
Materials Science · Mathematics · Physics and Astronomy · #2D Materials and Applications #Condensed matter physics #Electron #Graphene research and applications #Materials science #Mathematics #Phase transition #Physics #Quantum #Quantum Hall effect #Quantum critical point #Quantum mechanics #Quantum phase transition #Quantum phases #Quantum spin Hall effect #Spin (aerodynamics) #Square (algebra) #Topological Materials and Phenomena #Topological order #Topology (electrical circuits) #Transition metal #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.92.085427
published in Physical Review B 92(8) (American Physical Society) · 15 pages,4 figures
arxiv created 2015/04/01 · openalex publication_date 2015/08/25 · arxiv updated 2015/09/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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\phantom\rule0.28em0ex(M=Mo,\phantom\rule0.28em0exW;\phantom\rule0.28em0exX=S,\phantom\rule0.28em0exSe,\phantom\rule0.28em0exTe), 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.