Axion Mie Theory of Electron Energy Loss Spectroscopy in Topological Insulators

Abstract

Electronic topological states of matter exhibit novel types of responses to electromagnetic fields. The response of strong topological insulators, for instance, is characterized by a so-called axion term in the electromagnetic Lagrangian which is ultimately due to the presence of topological surface states. Here we develop the axion Mie theory for the electromagnetic response of spherical particles including arbitrary sources of fields, i.e., charge and current distributions. We derive an axion induced mixing of transverse magnetic and transverse electric modes which are experimentally detectable through small induced rotations of the field vectors. Our results extend upon previous analyses of the problem. Our main focus is on the experimentally relevant problem of electron energy loss spectroscopy in topological insulators, a technique that has so far not yet been used to detect the axion electromagnetic response in these materials.

Submission to SciPost

References in corpus (4)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Electric-Magnetic Duality and Topological Insulators
• Electromagnetic description of three-dimensional time-reversal invariant ponderable topological insulators
• Electromagnetic scattering by homogeneous, isotropic, dielectric-magnetic sphere with topologically insulating surface states