Hybridization of electric and magnetic responses in the effective axion background

TL;DR

This paper analyzes how oscillating electric or magnetic dipoles in a spherical region with a static axion field produce combined electric and magnetic fields, revealing new multipole effects in topological materials.

Contribution

It provides an analytical solution for electromagnetic fields in axion backgrounds, extending the Witten effect to dynamic multipole sources in complex materials.

Findings

Fields outside the sphere are superpositions of electric and magnetic dipoles.

The results enable probing P- and T-symmetry breaking in topological materials.

The approach applies to magneto-electrics, topological insulators, and metamaterials.

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.