Topological Properties in Strained Monolayer Antimony Iodide
Topological Properties in Strained Monolayer Antimony Iodide
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DOI：
10.1088/0256-307x/38/11/117301
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发表时间：
2021-10
影响因子：
3.5
通讯作者：
Danwen Yuan;Yuefang Hu;Yanmin Yang;A. W. Zhang
中科院分区：
文献类型：
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作者：
Danwen Yuan;Yuefang Hu;Yanmin Yang;A. W. Zhang
二维（2D）拓扑绝缘体呈现出物质的特殊相态，表现出独特的电子性质。迄今为止，已有许多单层结构的Sb二元化合物被报道为二维拓扑绝缘体，它们主要具有蜂窝结构。然而，对于单层正方晶格Sb化合物的拓扑绝缘性质的研究还很缺乏。在这里，通过第一性原理计算，提出了一个单层的SbI与正方形晶格，通过施加应变表现出可调的拓扑性质。在不同的应变水平下，单层SbI呈现出两种不同的结构相：屈曲方形结构和屈曲矩形结构，表现出吸引的拓扑性质。我们发现，在屈曲矩形相中，当应变大于3.78%时，系统经历了从非平凡拓扑绝缘体到平凡拓扑绝缘体的拓扑相变，相变点处的结构实际上是具有两个I型Dirac点的Dirac半金属.此外，该系统可以实现72.5 meV的拓扑绝缘体相的最大全局能隙，这意味着它在室温下的应用前景。本研究拓展了二维拓扑物理的研究范围，为探索低耗散量子电子器件提供了平台。
Two-dimensional (2D) topological insulators present a special phase of matter manifesting unique electronic properties. Till now, many monolayer binary compounds of Sb element, mainly with a honeycomb lattice, have been reported as 2D topological insulators. However, research of the topological insulating properties of the monolayer Sb compounds with square lattice is still lacking. Here, by means of the first-principles calculations, a monolayer SbI with square lattice is proposed to exhibit the tunable topological properties by applying strain. At different levels of the strain, the monolayer SbI shows two different structural phases: buckled square structure and buckled rectangular structure, exhibiting attracting topological properties. We find that in the buckled rectangular phase, when the strain is greater than 3.78%, the system experiences a topological phase transition from a nontrivial topological insulator to a trivial insulator, and the structure at the transition point actually is a Dirac semimetal possessing two type-I Dirac points. In addition, the system can achieve the maximum global energy gap of 72.5 meV in the topological insulator phase, implying its promising application at room temperature. This study extends the scope of 2D topological physics and provides a platform for exploring the low-dissipation quantum electronics devices.