Dynamical behavior of two-component spin systems in an alternating magnetic field

The nonequilibrium statistical operator method is used to consider the dynamics of a two-component isothermal magnetic system in an alternating magnetic field. Exact coupled equations of motion are obtained for the small deviations from equilibrium of the magnetizations of the subsystems, together with dispersion relations for the spectra of the normal modes and exact general expressions for the matrix Green's functions, the dynamic magnetic susceptibility, and the power absorbed in the external field. A self-consistent approach is formulated for the calculation of these quantities in terms of the exact characteristics of the noninteracting subsystems.