Localized Moments Associated with Very Dilute Fe Impurities in Some Transition and Noble Metals

The magnetic behavior of very dilute (<0.1%) iron impurities in Cu, Ag, Au, V, Nb, Ta, Mo, W, Rh, and Pt has been studied by the Mössbauer effect in ${\mathrm{Fe}}^{57}$ for applied fields to 62 kOe and temperatures from 0.5 to 300°K. For V, Nb, and Ta the hyperfine field at the impurity nucleus corresponds directly to the applied field to within 1.5 kOe; no localized moment exists. For the other metals, an internal field is found which is antiparallel to the applied field. The functional behavior of the internal fields is analyzed in terms of localized magnetic states associated with the Fe impurities, which do not interact with one another, but are not, in general, completely free. The localized magnetic moments, which range to 6.0 ${\mu }_B$, can be correlated with the average concentration of electrons outside the last full shell, and agree with the moments derived from available magnetic-susceptibility measurements. Temperature and chemical shifts for these sources are given.