Temperature dependent scattering from Cr impurities in Pd

The incremental resistivity Δ?(T) associated with small amounts (between 0.05 and 0.3 at% Cr) of Cr in Pd has been measured between 1.4 and 300 K and has been assumed to contain two principle contributions. The first decreases monotonically with increasing temperature, while the second consists of a rapid increase in Δ?(T) with increasing temperature between 15 and 60 K and has been attributed to conventional deviations from Matthiessen's rule (DMR). With the latter assumed to temperature independent above 70 K, Δ?(T > 70 K) has been fitted to

$\text{Δ?(T) = Ac + Bc 1n(T}{}^2\text{+ T}{}^2{}_{\mathrm{s}}\text{)}{}^{\mathrm{1/2}}$

yielding a concentration independent estimate of T_s ? 44 K. By comparing the experimental data with the extention of the above equation at temperatures below 70 K it is possible to estimate both the conventional DMR and the coefficient of the T² term predicted at low temperatures. While the former are in reasonable agreement with DMR observed in dilute non-magnetic Pd alloys, the T² coefficients measured in Δ?(T ? T_s) differ from their predicted values. Sources for this discrepency are discussed.