Abstract
Physikalisches Institut, Universita¨t Bayreuth, D-95440 Bayreuth, Germany~Received 2 April 1997!We identify the isolated giant moments associated with Fe impurities in a Pd matrix as a spin-fluctuationsystem with a spin-fluctuation temperature of ’250 mK. This conclusion is achieved from the temperaturedependence of the resistivity of 2.5 and 16 ppm Fe containing samples, extracted from the real part of the acelectrical impedance measured at 0.1 mK<T<600 mK, 0.1 mT<B,10 mT, and f5175 Hz. The effect ofgiant moments, which interact with others, on the resistivity is also discussed. The imaginary part of the acelectrical impedance, which is proportional to the ac susceptibility, reveals spin-glass freezing at around 1 mK,two orders of magnitude smaller than the spin-fluctuation temperature. This spin-glass freezing is confirmed bythe characteristic slow relaxation of dc magnetization below the spin-glass transition temperature.@S0163-1829~97!09634-3#I. INTRODUCTION
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