Disordered structures in ultracold spin-imbalanced Fermi gas

TL;DR

This paper explores the complex disordered and ordered structures in spin-imbalanced ultracold Fermi gases at low temperatures, revealing various phases including droplets, liquid-crystal-like arrangements, and potential supersolid states through microscopic calculations.

Contribution

It introduces a comprehensive theoretical analysis of disordered and ordered phases in spin-imbalanced Fermi gases without symmetry constraints, highlighting new structural phenomena.

Findings

Formation of spin-polarized droplets at low polarization

Disordered liquid-crystal-like structures at intermediate polarization

Emergence of supersolid-like regularities at high polarization

Abstract

We investigate properties of spin-imbalanced ultracold Fermi gas in a large range of spin polarizations at low temperatures. We present results of microscopic calculations based on mean-field and density functional theory approaches, with no symmetry constraints. At low polarization values we predict the structure of the system as consisting of several spin-polarized droplets. As the polarization increases, the system self-organizes into a disordered structures similar to liquid crystals, and energetically they can compete with ordered structures such as grid-like domain walls. At higher polarizations the system starts to develop regularities that, in principle, can be called supersolid, where periodic density modulation and pairing correlations coexist. The robustness of the results has been checked with respect to temperature effects, dimensionality, and the presence of a trapping potential. Dynamical stability has also been investigated.