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Radha, Santosh Kumar; Lambrecht, Walter R. L.
Physical review. B, 09/2020, Letnik: 102, Številka: 11Journal Article
Higher order topological tnsulators are d-spatial dimensional systems featuring topologically protected gapless states at their (d − n) -dimensional boundaries. With the help of ab initio calculations and tight-binding models along with symmetry considerations, we show that monolayer buckled honeycomb structures of group-V elements (Sb, As), which have already been synthesized, belong in this category and have a spinless charge fractionalization of e/2 at the corner states as well as weak topological edge states, protected by the S6 symmetry operation, which classify this system as a quadrupole topological insulator. The robustness of these edge and corner states to perturbations is explicitly demonstrated.
