Attenuated total reflection study of bulk and surface polaritons in antiferromagnets and hexagonal ferrites: Propagation at arbitrary angles

Abstract

We perform a theoretical study of the reflection of infra-red radiation from antiferromagnets and M-type barium hexagonal ferrite using an attenuated total reflection (ATR) geometry. At an arbitrary angle of propagation, the electromagnetic waves in the magnetic materials cannot be separated into the usual pure transverse electric (TE) and pure transverse magnetic (TM) modes. We develop a method to solve for the ATR reflection for arbitrary angles of propagation. Using reflection maps, one can determine the dispersion relations for both bulk and surface polaritons. We find that surface polariton features in the reflection map are present at all angles for both incident TE and TM polarizations, with the exception of TM polarization when the plane of incidence is perpendicular to the applied magnetic field. We also see that the interaction of the incident electromagnetic wave with surface polaritons can cause significant transfer from TE to TM modes (and vice versa) upon reflection. When the surface modes vanish, we see that the remaining bulk mode displays reciprocal behavior.