Surface polaritons on semi-infinite gyromagnetic media

A macroscopic theory of surface polaritons on semi-infinite magnetic media is presented. The general nature of surface polaritons on magnetic media is discussed. In the configuration k, M0, and n mutually perpendicular (where k is the propagation wavevector, M0 is the static magnetization of the medium, and n is the outward normal to the surface), the surface polaritons are TE modes with H elliptically polarized in the sagittal plane. The surface polaritons, which exist on a ferromagnetic insulator, exhibit nonreciprocal propagation characteristics of a medium with gyromagnetic permeability. A new branch of the surface polariton dispersion curve is demonstrated. The corresponding magnon type surface polaritons do not occur on a ferromagnetic metal. The possible experimental observation of the magnon type surface polariton modes on a ferromagnetic insulator is also discussed.