Floquet interface states in illuminated three-dimensional topological insulators

TL;DR

This paper explores how illuminating three-dimensional topological insulators with circularly polarized lasers creates Floquet-Bloch bands with non-trivial topology, and demonstrates that interfaces between counter-rotating lasers host spin-polarized chiral states.

Contribution

It proposes a novel setup with counter-rotating lasers inducing interface states in topological insulators, revealing new spin-polarized chiral states at laser interfaces.

Findings

Counter-rotating lasers induce chiral interface states.

Interface states are spin-polarized.

Potential applications in optoelectronics and spintronics.

Abstract

Recent experiments showed that the surface of a three dimensional topological insulator develops gaps in the Floquet-Bloch band spectrum when illuminated with a circularly polarized laser. These Floquet-Bloch bands are characterized by non-trivial Chern numbers which only depend on the helicity of the polarization of the radiation field. Here we propose a setup consisting of a pair of counter-rotating lasers, and show that one-dimensional chiral states emerge at the interface between the two lasers. These interface states turn out to be spin-polarized and may trigger interesting applications in the field of optoelectronics and spintronics.