  We discuss peculiarities of bulk and surface polaritons propagating in a
composite magnetic-semiconductor superlattice influenced by an external static
magnetic field. Three particular configurations of magnetization, namely the
Voigt, polar and Faraday geometries are considered. In the long-wavelength
limit, involving the effective medium theory, the proposed superlattice is
described as an anisotropic uniform medium defined by the tensors of effective
permittivity and effective permeability. The study is carried out in the
frequency band where the characteristic resonant frequencies of the underlying
constitutive magnetic and semiconductor materials of the superlattice are
different but closely spaced. The effects of mode crossing and anti-crossing in
dispersion characteristics of both bulk and surface polaritons are revealed and
explained with an assistance of the concept of Morse critical points from the
catastrophe theory.
