Linear response of heat conductivity of normal-superfluid interface of a polarized Fermi gas to orbital magnetic field

TL;DR

This paper investigates how a weak orbital magnetic field influences heat conductivity at the normal-superfluid interface of a polarized Fermi gas, revealing controllable effects relevant for magnetic sensors.

Contribution

It provides an analytical and numerical study of the heat conductivity response to orbital magnetic fields in polarized Fermi gases, including the effects of species imbalance and Andreev reflection.

Findings

Heat conductivity increases with species imbalance under orbital fields.

The effect of the magnetic field on heat conductivity is more prominent at higher temperatures.

Analytical expressions for transmission coefficients and heat conductivity are derived for the BCS regime.

Abstract

Using perturbed Bogoliubov equations, we study the linear response to a weak orbital magnetic field of the heat conductivity of the normal-superfluid interface of a polarized Fermi gas at sufficiently low temperature. We consider the various scattering regions of the BCS regime and analytically obtain the transmission coefficients and the heat conductivity across the interface in an arbitrary weak orbital field. For a definite choice of the field, we consider various values of the scattering length in the BCS range and numerically obtain the allowed values of the average and species-imbalance chemical potentials. Thus, taking Andreev reflection into account, we describe how the heat conductivity is affected by the field and the species imbalance. In particular, we show that the additional heat conductivity due to the orbital field increases with the species imbalance, which is more noticeable at higher temperatures. Our results indicate how the heat conductivity may be controlled, which is relevant to sensitive magnetic field sensors/regulators at the interface.