Spin-heat relaxation and thermospin diffusion in atomic Bose and Fermi gases

Abstract

We study spin-dependent heat transport in quantum gases, focusing on transport phenomena related to pure spin currents and spin-dependent temperatures. Using the Boltzmann equation, we compute the coupled spin-heat transport coefficients as a function of temperature and interaction strength for energy-dependent s-wave scattering. We address the issue of whether spin-dependent temperatures can be sustained on a time and length scale relevant for experiments by computing the spin-heat relaxation time and diffusion length. We find that the time scale for spin-heat relaxation time diverges at low temperatures for both bosons and fermions, indicating that the concept of spin-heat accumulation is well defined for degenerate gases. For bosons, we find power-law behavior on approach to Bose condensation above the critical temperature, as expected from the theory of dynamical critical phenomena.