Exact solution of the Boltzmann equation for low-temperature transport coefficients in metals II: Scattering by ferromagnons

Abstract

In a previous paper (Paper I) we developed a technique for exactly solving the linearized Boltzmann equation for the electrical and thermal transport coefficients in metals in the low-temperature limit. Here we adapt this technique to determine the magnon contribution to the electrical and thermal conductivities, and to the thermopower, in metallic ferromagnets. For the electrical resistivity ρ at asymptotically low temperatures we find ρ ∝ exp (−Tmin/T ), with Tmin an energy scale that results from the exchange gap and a temperature independent prefactor of the exponential. The corresponding result for the heat conductivity is σ h ∝ T 3 exp (Tmin/T ), and thermopower is S ∝ T . All of these results are exact, including the prefactors.