Magnetic Susceptibility of Copper-Nickel and Silver-Palladium Alloys at Low Temperatures

The magnetic susceptibilities of copper-nickel alloys with up to 39 atomic percent nickel and silver-palladium alloys with up to 10 atomic percent palladium have been measured by the Gouy method at temperatures between 295°K and 2.1°K. Measurements are reported on samples with an impurity content of less than 10 parts per million and on samples with greater impurity content. The susceptibility is nearly temperature-independent for all the silver-palladium alloys and for the copper-nickel alloys with up to 27% nickel. Higher nickel concentrations give rise to a $\frac{1}{T}$ susceptibility term which is too large to be accounted for by impurity content. The simple band model of Mott adequately describes the susceptibility of the silver-palladium alloys but fails to predict the large temperature-independent paramagnetic contribution of nickel in copper. Exchange energies calculated by the Stoner collective electron method for the copper-nickel alloys, using specific heat and susceptibility data, are somewhat unsatisfactory and suggest the presence of another mechanism.