文献类型：期刊文献

英文题名：Hidden higher-order topology in nonsymmorphic group IV and V tetragonal monolayers

作者：Xue, Yang[1];Xu, Wei[2,3,4];Zhao, Bao[2,3,4,5];Yang, Zhongqin[2,3,4,6]

机构：[1]East China Univ Sci & Technol, Sch Phys, Shanghai 200237, Peoples R China;[2]Fudan Univ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China;[3]Fudan Univ, Key Lab Computat Phys Sci MOE, Shanghai 200433, Peoples R China;[4]Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China;[5]Liaocheng Univ, Sch Phys Sci & Informat Technol, Shandong Key Lab Opt Commun Sci & Technol, Liaocheng 252059, Peoples R China;[6]Shanghai Qi Zhi Inst, Shanghai 200030, Peoples R China

年份：2024

卷号：109

期号：7

外文期刊名：PHYSICAL REVIEW B

收录：;EI(收录号：20240715546006);WOS:【SCI-EXPANDED(收录号:WOS:001198639300002)】；

基金：This work was supported by National Natural Science Foundation of China under Grants No. 11904101, No. 11604134, No. 12174059, and No. 11874117, and the Natural Science Foundation of Shanghai under Grant No. 21ZR1408200.

语种：英文

外文关键词：Crystalline materials - Germanium compounds - Topology

摘要：In recent years, two-dimensional (2D) second-order topological insulators (SOTIs) have garnered significantinterest, with indications of their potential realization in various symmorphic 2D electronic materials. However,up to this point, no nonsymmorphic 2D electronic SOTIs have been identified, probably due to the inability ofnonsymmorphic operations to maintain the invariance of nanoflakes. In this paper, we investigate the existenceof nonsymmorphic 2D SOTIs, unveiling hidden higher-order topology within 2D nonsymmorphic electronicsystems. Our findings are substantiated by symmetry analyses, tight-binding (TB) models, and first-principlescalculations. The emergence of topological corner states in these nonsymmorphic 2D SOTIs is attributed tothe filling anomaly within a set of symmorphic Wannier orbitals, which exhibit a symmorphic distribution. Weidentify square-octagon monolayers (so-MLs) of group IV and V elements, including 2D tetragonal P, and 2Dhydrogenated tetragonal Si and Ge, as promising material candidates. The corner states in these nonsymmorphicso-MLs are protected by a point symmetry (C4rotation). The TB model of so-MLs behaves similarly to theSu-Schrieffer-Heeger model, with higher-order topological insulating phases having greater intersquare hoppingscompared to intrasquare hoppings, while the reverse is considered trivial. These discoveries not only enrichour theoretical comprehension of higher-order topology but also introduce potential material candidates forexperimental exploration, thus advancing the field of topological crystalline materials