文献类型：期刊文献

英文题名：Second-order topological insulator and its transition to quantum spin Hall state in a hydrogenated tetragonal stanene

作者：Xu, Wenting[1,2,3];Xue, Yang[4];Zhu, Ye[1,2,3];Xu, Wei[1,2,3];Yang, Zhongqin[1,2,3,5]

机构：[1]Fudan Univ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China;[2]Fudan Univ, Key Lab Computat Phys Sci MOE, Shanghai 200433, Peoples R China;[3]Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China;[4]East China Univ Sci & Technol, Sch Phys, Shanghai 200237, Peoples R China;[5]Shanghai Qi Zhi Inst, Shanghai 200030, Peoples R China

年份：2024

卷号：8

期号：7

外文期刊名：PHYSICAL REVIEW MATERIALS

收录：;EI(收录号：20242816660329);WOS:【SCI-EXPANDED(收录号:WOS:001261762600005)】；

基金：This paper was supported by National Natural Science Foundation of China (Grants No. 12174059, No. 11874117, and No. 11904101) and Natural Science Foundation of Shanghai (Grant No. 21ZR1408200). The calculations were performed at High Performance Computational Center (HPCC) of the Department of Physics at Fudan University.

语种：英文

外文关键词：Binary alloys - Electric insulators - Lead alloys - Monolayers - Quantum chemistry - Quantum theory - Stability - Tensile strain - Tin alloys - Topological insulators

摘要：Two-dimensional (2D) group-IV materials with tetragonal structures have attracted considerable attention recently due to their structural stability and distinctive electronic and optical characteristics. However, topological quantum states, particularly second-order topological insulators (SOTIs), are seldom reported in them. Based on first-principles and tight-binding (TB) model calculations, we find that 2D hydrogenated tetragonal stanene (T-SnH) is an exotic SOTI, identified by the second Stiefel-Whitney number w2 = 1, along with robust corner states. Intriguingly, the SOTI in T-SnH transforms into a quantum spin Hall insulator under 2.7% tensile strain. The same topological phase transition can also occur by substituting the Sn element with the Pb element, namely, forming a T-PbH monolayer. A three-orbital TB model is constructed to understand the phase transition mechanism for the two schemes, both associated with band inversion between antibonding s and bonding px,y states due to the large Sn-Sn (or Pb-Pb) bond lengths. The phase transition is also rationalized well from topological quantum chemistry theory. These insights are helpful for understanding the SOTI and provide a promising material platform for topological quantum device designs and applications.