Abstract

We examine excitons formed in the bulk of a topological insulator as the system is tuned via a parameter between topological and trivial insulating phases, arguing that nontrivial topology has fingerprints in the spectrum of these excitons. The closely related hydrogen atom problem is well known to have a degeneracy due to a hidden symmetry, and the changes to the excitonic spectrum that we find can be understood as a result of breaking of this underlying symmetry due to the Berry phase. Furthermore, this phase is found to affect the spectrum in the topological parameter regime much more strongly than in the trivial regime. We first construct a semiclassical model of the system to develop qualitative intuition for the effects at play, then we move to a more robust numerical simulation of the full quantum system, working with the Bernevig-Hughes-Zhang model of a two-dimensional topological insulator.

Publication Details
Publication Type
Journal Article
Year of Publication
2018
Volume
98
DOI
10.1103/PhysRevB.98.045430
Journal
Physical Review B
Contributors