Surface plasmon resonance in the presence of topological insulators

The plasmonic resonance of the free electrons at a metal-topological insulator interface is studied with the application of axion electrodynamics. The additional red-shift due to the axion field previously observed in the literature is accounted for by a mechanical model similar to that used in the hybridization model for coupled plasmonic resonances in metallic nanoshells. Such model sheds light on the origin of the red-shift being caused by the decrease in interaction potential energy for the free electron fluid due to the axion-induced charges at the interface of the metal and the topological insulator.