A Unitary Fermi Supersolid: The Larkin-Ovchinnikov Phase

TL;DR

This paper provides strong theoretical evidence that the Larkin-Ovchinnikov phase is energetically favored over other phases in three-dimensional unitary Fermi systems, characterized by oscillating densities and pairing fields, with implications for understanding superfluidity.

Contribution

The study introduces a Density Functional Theory approach based on quantum Monte-Carlo data to demonstrate the stability of the LOFF phase in unitary Fermi gases across a broad phase diagram region.

Findings

LOFF phase is favored over homogeneous superfluid and normal phases.

Oscillations in density and pairing fields have large amplitude and specific periodicity.

Transitions to normal and superfluid phases are smooth and abrupt, respectively.

Abstract

We present strong theoretical evidence that a Larkin-Ovchinnikov (LOFF/FFLO) pairing phase is favoured over the homogeneous superfluid and normal phases in three-dimensional unitary Fermi systems. Using a Density Functional Theory (DFT) based on the latest quantum Monte-Carlo calculations and experimental results, we show that this phase is competitive over a large region of the phase diagram. The oscillations in the number densities and pairing field have a substantial amplitude, and a period some 3 to 10 times the average interparticle separation. Within the DFT, the transition to a normal polarized Fermi liquid at large polarizations is smooth, while the transition to a fully-paired superfluid is abrupt.