Theoretical study of hyperfine fields at diluted s-p, noble, and nd impurities in ferromagnetic compounds GdX (X=Zn, Cd)

The hyperfine fields at nd (n=3,4,5) impurities and at noble impurities dil uted in ferromagnetic compounds GdX (X=Zn, Cd) are discussed in the framewo rk of a two center model. In these systems it is observed that all impuriti es enter substitutionally at the "nonmagnetic" X lattice site, thus creatin g a strong local charge perturbation. In our model, one calculates the loca l magnetic moment in the charge perturbed conduction band at the origin. Th e magnetization of the s-p conduction band arises from the Gd 4f moments. T hen one obtains the conduction electron polarization contribution to the hy perfine field. The transition (and noble) impurities also create an Anderso n-Moriya d resonance in the strongly perturbed Slater-Koster local density of states at the origin, thus originating an additional local moment and th ereby a core polarization contribution to the magnetic hyperfine field. The self-consistently calculated hyperfine fields are in quite good agreement with available experimental data. (C) 2000 American Institute of Physics. [ S0021-8979(00)64008-2].