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.
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- 1 Johannes Schultz,
- 1 Flavio Nogueira,
- 1 2 3 Bernd Buechner,
- 1 2 3 Jeroen van den Brink,
- 1 2 Axel Lubk
- 1 Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden / Leibniz Institute for Solid State and Materials Research [IFW]
- 2 Technische Universität Dresden / Dresden University of Technology [TUD]
- 3 Würzburg-Dresden Cluster of Excellence [ct.qmat]