Dislocation as a bulk probe of higher-order topological insulators

Higher-order topological (HOT) states extend this usual bulk-boundary correspondence, so they host the modes localized at lower-dimensional boundaries, such as corners and hinges, which may hinder their experimental detection. We theoretically demonstrate that dislocations, ubiquitous defects in crystalline materials, can probe higher-order topology [1]. We show that both two- and three-dimensional HOT insulators respond to the dislocations through the protected finite-energy in-gap electronic modes, localized at the defect core, which originate from the interplay between the orientation of the HOT mass domain wall and the Burgers vector of the dislocation. The protection mechanism is based on non-crystalline symmetries, such as time-reversal and particle-hole, the crystalline ones, and may also involve their combination. Finally, we will discuss the consequences of our results for the systematic probing of the extended bulk-boundary correspondence in a broad range of HOT crystals and metamaterials through the lattice dislocation defects, controllable in state-of-the-art experiments.

[1] B. Roy and V. Juricic, arXiv:2006.04817