Itinerant-3d-electron spin-density oscillations surrounding solute atoms in Fe

A previous method of analysis of hyperfine-field spectra of dilute Fe-based alloys with transition solute atoms to the right of Fe in the periodic table is extended to obtain the solute- and host-moment perturbations of dilute Fe-based alloys with any $3d$ or $4d$ transition element. The resulting host-moment perturbations show very simple oscillatory behavior which can be interpreted as due to spin density oscillations in the itinerant $d$ electrons. It is shown that these spin density oscillations can be thought of as arising from the polarization induced in the itinerant $d$ electrons by the localized $d$ moment via mainly Coulomb exchange interactions, whereas the localized moments arise from the intra-atomic exchange interaction between the localized $d$ electrons. Within this scheme a purely itinerant band ferromagnetism is not plausible. The value of the Curie temperature of Fe is shown to be in good agreement with the interpretation. The features that are important in determining alloy behavior are clearly seen in this analysis and are enumerated and discussed. The contrast in behavior with dilute Ni-based alloys is also briefly discussed.