Negative temperature coefficient of electrical resistivity in disordered metallic alloys

Abstract

We discuss the existing models for negative temperature coefficients of resistivity in liquid and amorphous metallic alloys. Using a simplified average-$t$-matrix approximation calculation, we confirm an idea of Markowitz that such coefficients can arise from the inclusion of mixing between the phonon and potential scattering mechanisms. We further show that the negative values are a consequence of large electron self-energies when the Fermi energy lies in a region of low-density of states. We illustrate our ideas with approximate coherent-potential approximation calculations which yield good agreement with data for liquid Ce-Sn and amorphous Pd-Ni-P alloys, and suggest an approach for future work.