Radiation of a short linear antenna above a topologically insulating half-space

The topological magnetoelectric effect is a unique macroscopic manifestation of quantum states of matter possessing topological order and it is described by axion electrodynamics. In three-dimensional topological insulators, for instance, the axion coupling is of the order of the fine structure constant, and hence, a perturbative analysis of the field equations is plenty justified. In this paper, we use Green’s function techniques to obtain time-dependent solutions to the axion field equations in the presence of a planar domain wall separating two media with different topological order. We apply our results to investigate the radiation of a short linear antenna near the domain wall.