The hyperfine field at rare-earth impuritiesdiluted in Fe, Co and Ni hosts: a theoretical study

Abstract

In this work we study the magnetic moments and the hyperfinefields at rare-earth impurities diluted in Fe, Co and Niferromagnetic hosts. We use an Anderson-like model in which adegenerate localized 4f energy level of the rare-earthimpurity is hybridized with a spin-polarized d-electronband. We use the Hartree-Fock approximation to deal with theelectron-electron interactions and include the nearest-neighbourperturbation, due to the d translational invariancebreaking introduced by the impurity. Our numerical results showthat the systematics of the hyperfine fields changes sign in themiddle of the rare-earth series and exhibits a strong orbitalcontribution for most of the rare-earth impurities, ingood agreement with experimental data.