Photocurrent Response of Topological Insulator Surface States

TL;DR

This paper investigates the photocurrent response of topological insulator surface states under circularly polarized light, highlighting the dominance of helicity-independent currents and the effects of various perturbations.

Contribution

It provides a detailed theoretical analysis including perturbations like hexagonal warping and magnetic fields, emphasizing the role of Zeeman coupling in photocurrent response.

Findings

Helicity-independent photocurrent dominates over helicity-dependent contributions.

Photocurrent response is strongly suppressed by orbital coupling, but Zeeman coupling restores it.

Surface states modeled with Dirac Hamiltonian including perturbations.

Abstract

We study the photocurrent response of topological insulator surface states to circularly polarized light for arbitrary oblique incidence. We describe the surface states within a Dirac model, including several perturbations such as hexagonal warping, nonlinear corrections to the mode velocity, and applied magnetic fields. We find that the photogalvanic current is strongly suppressed for the usual orbital coupling, prompting us to include the weaker Zeeman coupling. We find that the helicity-independent photocurrent dominates over the helicity-dependent contributions.