Conventional crystal defect as a probe of topology

Besides topological lattice defects, such as dislocations and disclinations, crystals are also accompanied by unavoidable ordinary defects, among which vacancies, Schottky defects, substitutions, interstitials, and Frenkel pairs are the most common and prominent ones. In this work, we show that such inevitable crystal defects can probe topology of electronic Bloch bands in terms of bound states in their vicinity that are robust against weak pointlike charge impurities. We establish these (possibly) generic findings by implementing a minimal model Hamiltonian describing time-reversal symmetry breaking topological and normal insulators on a square lattice, fostering such point defects therein.