Spinning radiation from a topological insulator

Abstract

Axion coupling in topological insulators dramatically changes the electromagnetic response of these materials. Here, the authors show that this coupling leads to the emergence of spin angular momentum in the associated thermal radiation where all emitted light is elliptically polarized in the same direction. In contrast to conventional thermal emitters with a structured interface, a slab of a topological insulator with a thin magnetic coating would radiate thermal photons with the same magnitude and direction of circular polarization in all emission angles.