On the origin of localized magnetic states in transition metal alloys I. Wolff model

Abstract

AbstractThe generalized Wolff Hamiltonian is solved in approximations which are exact in the limit of isolated impurity. It is shown that approximations analogical to those developed by Hubbard in the narrow band Hamiltonian overestimate the effect of Coulomb correlations. The formation of localized magnetic moments is described in the selfconsistent approach, which conserves first four moments of the spectral density function. The results indicate that the degeneracy of impurity levels is essential for transition metal systems.