Optical Conductivity of Topological Insulator Thin Films in a Quantizing Magnetic Field

TL;DR

This paper investigates the optical conductivity of topological insulator thin films under a magnetic field, revealing how hybridization and Zeeman effects influence phase transitions and optical responses.

Contribution

It provides a detailed analysis of the magneto-optical response distinguishing topological from normal phases and identifies how hybridization gaps can be experimentally determined.

Findings

Optical response differs significantly between topological and normal phases.

Magneto-optical response can identify phase transitions.

Hybridization gap can be extracted from optical measurements.

Abstract

We determine the optical response of topological insulator thin films in the presence of a quantizing, external magnetic field. We explicitly take into account hybridization between the states of top and bottom surface. The interplay between hybridization and Zeeman energies gives rise to topological and normal insulator phases and phase transitions between them. The optical response in the two phases and at the phase transition point is investigated. We show that the difference in magneto-optical response can be used to distinguish the topological phase from the normal phase of the system. Further, the optical response also allows us to determine the gap generated by hybridization between top and bottom surface states of topological insulator thin films.