Effect of Interactions on the Kondo Resistivity of DiluteAuFeAlloys

Measurements are presented of the resistivity of a number of $\mathrm{Au}\mathrm{Fe}$ alloys with concentrations varying from 0.002- to 2- at.% Fe in the temperature range 0.45-40 °K. Very dilute $\mathrm{Au}\mathrm{Fe}$ alloys have already been found to obey an equation due to Hamann. The more concentrated alloys studied here show departures from Hamann's equation due to interactions between the impurities, and these have been taken into account by assuming that they modify the Hamann equation by a factor ($1-\frac{{\gamma }^{\prime }}{T^2}+\frac{{\delta }^{\prime }}{T^4}$). It is found that for concentrations greater than 0.01-at.% Fe, the spin resistivity no longer increases linearly with concentration; it is suggested that this is due to correlations between partially formed spin-compensated states. It is also found that the internal field distribution in $\mathrm{Au}\mathrm{Fe}$ alloys can be approximated by a Gaussian. In the most concentrated alloys, the low-temperature resistivity varies linearly with temperature with a slope which is independent of concentration, in agreement with theoretical prediction.