Spin fluctuations of isolated Fe impurities in Pd-based dilute alloys: effect of ferromagnetichost spin polarization

Abstract

The magnetic moment and spin fluctuation temperatureTSF of isolated Fe atoms in a number of Pd-based binary alloys, namelyPd0.95M0.05 (M = Ni,Rh, Mo, Ag, Cd, In, Sn, Th and U), have been determined from the local susceptibilityχloc(T) of54Fe probe nuclei measured by means of the time differential perturbedangular distribution (TDPAD) technique. Depending on the element Madded to the Pd matrix, the results derived from Curie–Weiss analysis,χloc(T) = C/(T+TSF), reveal strong enhancement or suppression of the ferromagnetic host spin polarizationSh associated with the giant moment of Fe. Concurrent with the variation in host spinpolarization, we have observed a large change in the spin fluctuation temperatureTSF, showing an exponential rise with diminishing value ofSh. The results, analysed on the basis of the Kondo model, indicate that spin fluctuationscaused by the antiferromagnetic interaction associated with the negative conductionelectron spin polarization are suppressed progressively by an incremental addition of apositive contribution to the effective exchange interaction.