Chandrasekhar-Clogston limit and critical polarization in a Fermi-Bose superfluid mixture

TL;DR

This paper investigates how interactions with a Bose-Einstein condensate affect the critical polarization for superfluidity breakdown in a population-imbalanced Fermi gas, providing theoretical predictions for experimental setups.

Contribution

It introduces a model for Fermi-Bose mixtures at zero temperature, showing the enhancement of the Chandrasekhar-Clogston limit due to bosonic interactions and analyzing trapped configurations.

Findings

Critical polarization is increased by bosonic interactions.

Predictions made for trapped Fermi-Bose mixtures with equal coupling constants.

Potential to observe exotic phases like FFLO and spin domains.

Abstract

We study mixtures of a population-imbalanced strongly-interacting Fermi gas and of a Bose-Einstein condensed gas at zero temperature. In the homogeneous case, we find that the Chandrasekhar-Clogston critical polarization for the onset of instability of Fermi superfluidity is enhanced due to the interaction with the bosons. Predictions for the critical polarization are also given in the trapped case, with a special focus to the situation of equal Fermi-Bose and Bose-Bose coupling constants, where the density of fermions becomes flat in the center of the trap. This regime can be realized experimentally using Feshbach resonances and is well suited to investigate the emergence of exotic configurations, such as the occurrence of spin domains or the FFLO phase.