Specific Heat of Dilute Solutions of Fe in Cu–Al Alloys

Abstract

The specific heat of Cu–Al and Cu–Al:Fe alloys containing 0, 5, and 10 at.% Al and 0.07 at.% Fe has been measured in the temperature range 1.2° –14° K. The excess specific heat due to the Fe impurities is decreased with increasing Al concentration. The data are compared with various predictions based on the Kondo model for dilute magnetic alloys. The decrease in the excess specific heat is consistent with the corresponding decrease in the magnetic moment of the Fe with increasing Al concentration determined by high-temperature susceptibility data. A further systematic change in the temperature dependence of the excess specific heat is attributed to an increase in the Kondo parameter TK with increasing Al. The measurements strongly support the hypothesis that the excess specific heat is associated with the Kondo effect, and that interactions among impurities is not the mechanism.