Coherent Magneto-Optical Effects in Topological Insulators: Excitation Near the Absorption Edge

TL;DR

This paper develops a theoretical framework for coherent magneto-optical effects in topological insulator surface states, highlighting nonlinear optical responses near the absorption edge influenced by the optical Stark effect.

Contribution

It introduces a theory for the dynamical Hall effect in topological insulators, incorporating nonlinear optical Stark effects and analyzing their impact on Faraday and Kerr rotations.

Findings

Nonlinear dependence of Faraday and Kerr rotations on optical field strength.

Decreased Faraday rotation with increasing electric field.

Non-monotonic Kerr rotation behavior.

Abstract

We study coherent optics in topological insulator surface states with broken time-reversal symmetry and develop a theory for the dynamical Hall effect driven by intense electromagnetic field. The influence of optical Stark effect enters as nonlinear dependence on the optical field in the resulting Faraday $\theta_F$ and Kerr $\theta_K$ rotations. This nonlinear correction is found to decrease $\theta_F$ with the strength of the A.C. electric field, whereas $\theta_K$ exhibits a non-monotonic behavior. We also assess the effects of relaxation and dephasing on the Hall and magneto-optical responses when the frequency detuning is comparable to the inverse lifetime of the conduction electrons.