Anomalous temperature dependence associated with conduction electron scattering from isolated Cr impurities in Pd and Pt

Abstract

The electrical resistivity of several dilute PtCr and PdCr alloys, containing between 0.05 and 0.3 at % Cr, has been measured from 1.4 to 300 K. The incremental resistivity Δp (T) appears to contain two contributions; the first arises from conventional Matthiessen’s Rule deviations, while the second contribution decreased monotonically with increasing temperature. With the conventional DMR assumed to be temperature-independent above about 60 K, it was found that the temperature dependence of the incremental resistivity Δρ (T≳60 K) in both systems was well represented by an expression of the form Δρ (T) =Ac+Bc ln (T2+T2)1/2. The single impurity characteristic temperature Ts was found to be concentration-independent in both systems with a value of Ts?45 K for PdCr and ?75 K for PtCr. The difference between the experimental values for Δρ (T) and the predicted form for Δρ (T) extended to low temperatures allowed a determination of the conventional DMR. The latter have been fitted to a ’’dirty limit’’ empirical model and are in good agreement with those deduced from previous measurements on nonmagnetic impurities in Pd and Pt. The latter result lends support to our assumption regarding the behaviour of the conventional DMR at high temperatures.