Spin-heat relaxation and thermo-spin diffusion in atomic Bose and Fermi gases

TL;DR

This paper investigates spin-dependent heat transport in quantum gases, analyzing how spin and heat currents behave and relax, with implications for experimental observation of spin-heat phenomena in Bose and Fermi gases.

Contribution

It provides a detailed calculation of spin and heat transport coefficients and relaxation times in quantum gases, revealing divergence at low temperatures and behavior near Bose condensation.

Findings

Spin-heat relaxation time diverges at low temperatures for both bosons and fermions.

Spin-dependent temperatures can be sustained in degenerate gases due to divergence in relaxation time.

Power-law behavior of relaxation time near Bose condensation for bosons.

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 and 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.