Wang Yonghu, Lei Shuangying, Wan Neng, Xu Feng, Yu Hong, Li Cuiyu, Chen Jie
Key Laboratory of Microelectromechanical Systems of the Ministry of Education, Southeast University, Nanjing 210096, China.
Advanced Computing East China Sub-center, Suma Technology Co., Ltd., Kunshan 215300, China.
J Phys Chem Lett. 2021 Dec 30;12(51):12202-12209. doi: 10.1021/acs.jpclett.1c03578. Epub 2021 Dec 17.
Two-dimensional (2D) topological insulators (TIs) have recently attracted a great deal of attention due to their nondissipation electron transmission, stable performance, and easy device integration. However, a primary obstacle to influencing 2D TIs is the small bandgap, which limits their room-temperature applications. Here, we adopted first-principles to predict inversion-asymmetric group IV monolayers, PbSn(CH) and PbSn(CH), to be quantum spin Hall (QSH) insulators with large topological gaps of 0.586 and 0.481 eV, respectively. The nontrivial band topologies, which can survive in a wide range of strain, are characterized by topological invariants Z, gapless edge states, and the Berry curvature. Another intriguing characteristic is the significant Rashba SOC effect which can also be tuned by feasible compressive and tensile strains. Meanwhile, the hexagonal boron nitride (-BN) provides a suitable substrate for growth of these films without influencing their topological phases. These novel materials are expected to accelerate the development of advanced quantum devices.
二维（2D）拓扑绝缘体（TIs）因其无耗散电子传输、稳定性能以及易于器件集成，近来备受关注。然而，影响二维拓扑绝缘体的一个主要障碍是其带隙较小，这限制了它们在室温下的应用。在此，我们采用第一性原理预测IV族反演不对称单层材料PbSn(CH)和PbSn(CH)分别为量子自旋霍尔（QSH）绝缘体，其拓扑带隙分别为0.586和0.481电子伏特。这些非平庸的能带拓扑结构能够在较宽的应变范围内保持，其特征包括拓扑不变量Z、无带隙边缘态以及贝里曲率。另一个有趣的特性是显著的Rashba自旋轨道耦合（SOC）效应，它也可以通过可行的压缩和拉伸应变进行调控。同时，六方氮化硼（h-BN）为这些薄膜的生长提供了合适的衬底，且不会影响它们的拓扑相。这些新型材料有望加速先进量子器件的发展。
