ISOELECTRONIC EARLY N-D IMPURITIES IN FE - MAGNETIC AND HYPERFINE FIELD PROPERTIES

The hyperfine fields and the local magnetic moments in a series of all oys of isoelectronic transition impurities diluted in iron are discuss ed. We intend to show that, even within a very simplified model, perio d effects for isoelectronic impurities at the beginning of an n-d seri es (e.g., Sc, Y, and Lu) are dominated by the charge difference effect , inducing a very strong repulsive potential. We find that the local i mpurity magnetic moments are very close to each other, leading to hype rfine fields, in fair agreement with experimental data. Our calculatio n accounts for the general trends of the local impurity moments in fer romagnetic Fe, despite quantitative deviations that do occur, due to t he very simple structure of this model. We point out, however, that ou r calculation is a starting point for a more refined one, dealing with rare-earth impurities (such as Eu, Gd, and Tb) placed in the Fe host, where the strong charge effects are present, together with f-spin sca ttering.