Interface and guided magnetic polariton modes in magnetic structure.

Abstract

We study the interface and guided magnetic polaritons for a three-layer system composed of a semi-infinite ferromagnet and a semi-infinite antiferromagnet separated by a dielectric layer of finite thickness. The single interface between a ferromagnet and an antiferromagnet is studied as a limiting case. Inversion of the magnetostatic limit of the interface polaritons with the bulk magnetic polaritons is predicted. For the two interfaces, evanescent and guided modes are predicted and their characteristics are studied. Integrated energy fluxes are calculated and their behaviors serve to indicate the field profiles in the three different media. In the case of overlapping gaps of bulk polaritons, a guided mode in the dielectric layer is shown to become stationary. The physical parameters used in the numerical evaluations are those of yttrium iron garnet and ${\mathrm{FeF}}_{2}$, and the thickness of the dielectric layer is fixed from these parameters.