Critical dynamics of a localized moment system coupled to conduction electrons

We discuss the critical dynamics of a system of localized spins interacting with conduction electrons via an isotropic exchange coupling between the respective spin densities. It is shown that the elimination of the conduction electrons by an adiabatic approximation is not allowed for small wave vectors. The quantum mechanical Fokker-Planck equation derived in a previous paper is used to investigate the renormalization of the kinetic coefficients due to nonlinear mode coupling contributions.