Surface and guided magnetic polaritons in a film with perpendicular uniaxial magnetic anisotropy

The dispersion relations of surface and guided polaritons in a ferromagnetic film are obtained for perpendicular magnetic anisotropy in the Voigt geometry. A new frequency window for guided modes is predicted for small external magnetic field. The frequency of surface-guided mode decreases at first as a function of intensity of the external magnetic field applied parallel to the film surface, then goes through a minimum and finally increases with the field intensity. The calculations are carried out for physical parameters now available in substituted iron garnet films.