Second-order topological insulator state in hexagonal lattices and its abundant material candidates
Second-order topological insulator state in hexagonal lattices and its abundant material candidates
We propose two mechanisms to realize the second-order topological insulator (SOTI) state in spinless hexagonal lattices, viz., chemical modification and anti-Kekul\'e/Kekul\'e distortion of hexagonal lattices. Correspondingly, we construct two models and demonstrate the nontrivial band topology of the SOTI state characterized by the second Stiefel-Whitney class ${w}_{2}$ in the presence …