Specific heat, magnetic susceptibility, and resistivity of an U0.85La0.15Al2 alloy

Abstract

The compound U${\mathrm{Al}}_2$ exhibits ferromagnetic spin fluctuations at low temperatures. When 15 at.% La is substituted for U in U${\mathrm{Al}}_2$, we find the low-temperature magnetic susceptibility increases by more than a factor of 2. We have also measured specific heat on this sample at low temperatures. We find that the electronic density of states has increased by 60% and the spin-fluctuation contribution has increased by a factor of 2. We conclude from these measurements that the Stoner enhancement factor has increased by ∼30% and the spin-fluctuation temperature has increased by ∼50% as compared with U${\mathrm{Al}}_2$. In addition, we have measured the electrical resistivity of ${\mathrm{U}}_{0.85}$ ${\mathrm{La}}_{0.15}$ ${\mathrm{Al}}_2$. We find the residual resistivity to be approximately an order of magnitude larger than that of U${\mathrm{Al}}_2$. We attribute this effect to the breaking of U—U bonds by the La atoms.