Spin-drag relaxation time in one-dimensional spin-polarized Fermi gases

TL;DR

This paper calculates the spin-drag relaxation time in one-dimensional spin-polarized Fermi gases, revealing an activation law at low temperatures and offering key data for spin transport modeling.

Contribution

It provides the first combined numerical and analytical analysis of spin-drag relaxation time in 1D polarized Fermi gases, highlighting a strong temperature dependence at low temperatures.

Findings

Activation law for spin-drag relaxation time at low temperatures

Stronger temperature dependence of the prefactor compared to previous models

Provides fundamental data for spin-density functional theory in 1D systems

Abstract

Spin propagation in systems of one-dimensional interacting fermions at finite temperature is intrinsically diffusive. The spreading rate of a spin packet is controlled by a transport coefficient termed "spin drag" relaxation time $\tau_{\rm sd}$. In this paper we present both numerical and analytical calculations of $\tau_{\rm sd}$ for a two-component spin-polarized cold Fermi gas trapped inside a tight atomic waveguide. At low temperatures we find an activation law for $\tau_{\rm sd}$, in agreement with earlier calculations of Coulomb drag between slightly asymmetric quantum wires, but with a different and much stronger temperature dependence of the prefactor. Our results provide a fundamental input for microscopic time-dependent spin-density functional theory calculations of spin transport in 1D inhomogeneous systems of interacting fermions.