Fulde-Ferrell-Larkin-Ovchinnikov state of two-dimensional imbalanced Fermi gases

TL;DR

This paper explores the stability and characteristics of the FFLO phase in two-dimensional imbalanced Fermi gases, revealing that the pairing amplitude can be comparable to the two-body binding energy and analyzing the zero-temperature gap equation.

Contribution

It provides a detailed analysis of the FFLO phase stability and properties in 2D imbalanced Fermi gases, including the magnitude of pairing and wavevector, using a non-Ginzburg-Landau approach.

Findings

FFLO phase stability regime identified

Pairing amplitude can be comparable to two-body binding energy

Nonanalyticities in the gap equation invalidate small $\

Abstract

The ground-state phase diagram of attractively-interacting Fermi gases in two dimensions with a population imbalance is investigated. We find the regime of stability for the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, in which pairing occurs at finite wave vector, and determine the magnitude of the pairing amplitude $\Delta$ and FFLO wavevector $q$ in the ordered phase, finding that $\Delta$ can be of the order of the two-body binding energy. Our results rely on a careful analysis of the zero temperature gap equation for the FFLO state, which possesses nonanalyticities as a function of $\Delta$ and $q$, invalidating a Ginzburg-Landau expansion in small $\Delta$.