Configuration fluctuations and the dilute-magnetic-alloy problem

A new theoretical treatment of the Anderson model of transition-metal or rare-earth impurities in a simple metal is presented. This study treats the impurity Coulomb correlation exactly and the host impurity coupling to lowest order in the sense of a self-consistent degenerate perturbation theory. The central result of this work is that if an impurity interconfigurational excitation energy (ICEE) is close to the Fermi energy in the atomic limit, a temperature-dependent shift of the ICEE is found for the interacting system. This temperature-dependent shift is shown to give a good description of the experimental observations on dilute magnetic alloys.