Vortex lattice in spin-imbalanced unitary Fermi gas

TL;DR

This paper explores the complex interplay of vortex lattice formation, phase separation, and FFLO states in a spin-imbalanced, rotating unitary Fermi gas using density functional theory, aligning theoretical predictions with experimental observations.

Contribution

It introduces a detailed theoretical analysis of vortex and phase structures in spin-imbalanced Fermi gases, highlighting the effects of different trapping potentials and the potential signatures of FFLO states.

Findings

Phase separation in harmonic traps with superfluid core and polarized corona.

Reversal of spatial component distribution in box traps with vortices.

Potential indirect evidence of FFLO state through exotic vortex geometries.

Abstract

We investigate the properties of a spin-imbalanced and rotating unitary Fermi gas. Using a density functional theory (DFT), we provide insight into states that emerge as a result of a competition between Abrikosov lattice formation, spatial phase separation and the emergence of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. A confrontation of the experimental data [M. Zwierlein et al., Science 311, 492 (2006)] with theoretical predictions provides a remarkable qualitative agreement. In case of gas confined in a harmonic trap, the phase separation into a superfluid core populated by the Abrikosov lattice and a spin-polarized corona is the dominant process. Changing confinement to a box-like trap, reverts the spatial location of the component: gas being in the normal state is surrounded by superfluid threaded by quantum vortices. The vortex lattice no longer exhibits the triangular symmetry, and emergence of exotic geometries may be an indirect signature of the FFLO-like state formation in the system.