Magnetopolaron states of a spin-correlated antiferromagnet in the neighborhood of the spin-glass transition

The problem of the spectrum of magnetopolaron states of a strongly correlated conducting canted antiferromagnet is solved. The approach used to study the spectrum is based on an atomic representation and a diagram technique for Hubbard operators. This approach makes it possible to include strong intra-ion interactions in a first-principles way, and to obtain the dispersion equation for the magnetopolaron spectrum for arbitrary values of the magnitude of the spin, temperature, and magnetic field. In the vicinity of the spin-flip transition an analytic expression is obtained for the spectrum of magnetopolaron states that goes beyond the framework of the quasiclassical approximation.