Hybridization of electric and magnetic responses in the effective axion background

Abstract

We investigate the electromagnetic fields produced by the oscillating point electric or magnetic dipole placed in a spherical volume with nonzero time-independent effective axion field. Our analytical solution shows that the fields outside the volume are a superposition of electric and magnetic dipole fields. Such multipole time-dependent generalization of the Witten effect can be realized in magneto-electrics, topological insulators or metamaterials providing a flexible probe of P- and T-symmetry breaking phenomena in different electromagnetic structures.