The role of interactions in spin-polarised atomic Fermi gases at unitarity

TL;DR

This paper investigates the properties of spin-polarized Fermi gases at unitarity, emphasizing the effects of interactions on phase separation, density profiles, and superfluid-normal phase boundaries, with results aligning closely with recent experiments.

Contribution

It introduces a theoretical framework combining quasi-particle formalism and Monte Carlo data to accurately predict properties of polarized Fermi gases at unitarity, including critical polarization and density profiles.

Findings

Predicted the Chandrasekhar-Clogston limit with high accuracy

Confirmed density jump at the phase interface experimentally

Discussed the Fermi liquid behavior in strongly interacting regimes

Abstract

We study the zero temperature properties of a trapped polarized Fermi gas at unitarity by assuming phase separation between an unpolarized superfluid and a polarized normal phase. The effects of the interaction are accounted using the formalism of quasi-particles to build up the equation of state of the normal phase with the Monte Carlo results for the relevant parameters. Our predictions for the Chandrasekhar-Clogston limit of critical polarization and for the density profiles, including the density jump at the interface, are confirmed with excellent accuracy by the recent experimental results at MIT. The role of interaction on the radial width of the minority component, on the gap of the RF transition and on the spin oscillations in the normal phase is also discussed. Our analysis points out the Fermi liquid nature of these strongly interacting spin polarized configurations.