具有可调带隙的二维拓扑绝缘体：单层碲化汞和硒化汞。
Two-dimensional topological insulators with tunable band gaps: Single-layer HgTe and HgSe.
作者信息
Li Jin, He Chaoyu, Meng Lijun, Xiao Huaping, Tang Chao, Wei Xiaolin, Kim Jinwoong, Kioussis Nicholas, Stocks G Malcolm, Zhong Jianxin
机构信息
Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan 411105, P. R. China.
Laboratory for Quantum Engineering and Micro-Nano Energy Technology and School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, P. R. China.
出版信息
Sci Rep. 2015 Sep 14;5:14115. doi: 10.1038/srep14115.
Two-dimensional (2D) topological insulators (TIs) with large band gaps are of great importance for the future applications of quantum spin Hall (QSH) effect. Employing ab initio electronic calculations we propose a novel type of 2D topological insulators, the monolayer (ML) low-buckled (LB) mercury telluride (HgTe) and mercury selenide (HgSe), with tunable band gap. We demonstrate that LB HgTe (HgSe) monolayers undergo a trivial insulator to topological insulator transition under in-plane tensile strain of 2.6% (3.1%) due to the combination of the strain and the spin orbital coupling (SOC) effects. Furthermore, the band gaps can be tuned up to large values (0.2 eV for HgTe and 0.05 eV for HgSe) by tensile strain, which far exceed those of current experimentally realized 2D quantum spin Hall insulators. Our results suggest a new type of material suitable for practical applications of 2D TI at room-temperature.
具有大带隙的二维（2D）拓扑绝缘体对于量子自旋霍尔（QSH）效应的未来应用至关重要。通过从头算电子计算，我们提出了一种新型的二维拓扑绝缘体，即单层（ML）低屈曲（LB）碲化汞（HgTe）和硒化汞（HgSe），其带隙可调。我们证明，由于应变和自旋轨道耦合（SOC）效应的结合，LB HgTe（HgSe）单层在2.6%（3.1%）的面内拉伸应变下会经历从平凡绝缘体到拓扑绝缘体的转变。此外，通过拉伸应变，带隙可以调至很大的值（HgTe为0.2 eV，HgSe为0.05 eV），这远远超过了目前实验实现的二维量子自旋霍尔绝缘体的带隙。我们的结果表明了一种适用于二维拓扑绝缘体室温实际应用的新型材料。
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