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Higher-order topological insulators in two-dimensional Dirac materials

2021; American Physical Society; Volume: 3; Issue: 4 Linguagem: Inglês

10.1103/physrevresearch.3.l042044

2643-1564

Xue Yang, H. Huan, Bao Zhao, You-Hua Luo, Zhenyu Zhang, Zhongqin Yang,

2D Materials and Applications

As a novel topological state, a higher-order topological insulator has attracted enormous interest, which in d spatial dimensions has gapless boundary states at (d−n) dimensions (integer n is larger than 1). Until now, merely few two-dimensional (2D) materials have been identified as higher-order topological insulators and their experimental confirmations are still absent. Here we propose a universal strategy of antidot engineering to realize second-order topological insulators (SOTIs) in 2D Dirac materials. Based on symmetry analysis, tight-binding model, and first-principles calculations, we demonstrate SOTIs in antidot-decorated Xene (X=C, Si,and Ge) by displaying its finite bulk quadrupole moment, weak topological edge states, and in-gap topological corner states. An inherent connection is established for the existing various mechanisms of the SOTIs, including quadrupole polarization, filling anomaly, and generalized Su-Schrieffer-Heeger model on a Kekulé lattice. The robustness of topological corner states of the SOTIs against edge perturbations and bulk disorders is explicitly demonstrated, rendering our strategy appealing to experimental realization of topological corner states.Received 5 September 2021Accepted 30 November 2021DOI:https://doi.org/10.1103/PhysRevResearch.3.L042044Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasEdge statesFirst-principles calculationsTopological materialsPhysical SystemsGermaneneGrapheneHoneycomb latticeTechniquesDensity functional theorySymmetriesTight-binding modelWannier function methodsCondensed Matter, Materials & Applied Physics