Higher-order topological insulators in two-dimensional Dirac materials

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