General existence conditions of polaritons in anisotropic, superconductive and isotropic systems

General conditions of existence of surface electromagnetic waves propagating along the anisotropic dielectric-superconductor and anisotropic dielectric-isotropic non-conductive medium interfaces are formulated under the assumption of the positive definiteness of dielectric permittivity tensors. It is shown that the problem of existence of surface polaritons is reduced to the investigation of limiting electromagnetic waves. For the boundary between an anisotropic medium and a superconductor it is established that the excitation of localized states is impossible for the majority of cuts and propagation directions. Exceptions are those directions which are determined by so-called exceptional body waves. For the boundary between an anisotropic and isotropic medium the dielectric permittivities of the latter at which surface waves can propagate are calculated.