MAGNETIC-BEHAVIOR OF DILUTE RH IMPURITIES IN AU1-XFEX ALLOYS - A PERTURBED-ANGULAR-CORRELATION STUDY

We have studied the local magnetic behavior of isolated Rh impurities in Au1-xFex alloys for compositions x=0.01, 0.03, 0.10, and 0.18, usin g the time-differential perturbed-angular-correlation (TDPAC) method a nd by electronic structure calculations within the local spin-density (LSD) approximation. From the measured Curie-Weiss local susceptibilit y of the Rh-100 probe as well as the LSD calculations we find large st able magnetic moments 0.5-1.0 mu(B) on Rh for compositions x greater t han or equal to 0.10. In low Fe concentration alloys the observed weak local susceptibility can be reconciled with the calculated large loca l moments, both positive and negative, on Rh in terms of a typical Rud erman-Kittel-Kasuya-Yosida (RKKY)-type mechanism between Fe and Rh. In the reentrant spin-glass regime, T less than or equal to 60 K for x=0 .18, the hyperfine field B-hf shows a two-step temperature dependence, increasing sharply below 60 K, such that its extrapolated value at 0 K is enhanced by 30% over its saturated value in the ferromagnetic reg ion.