Single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell state in BCS--Bose-Einstein condensation crossover

TL;DR

This paper investigates the stability of single-plane-wave LOFF states across the BCS-BEC crossover at various temperatures, highlighting the impact of noncondensed pairs on phase diagrams and the conditions under which LOFF phases remain ground states.

Contribution

It introduces a comprehensive analysis of LOFF states including noncondensed pairs, revealing their potential as ground states in a broad interaction range at finite temperatures.

Findings

LOFF phases can be ground states across a wide interaction spectrum

Non-zero temperature destabilizes LOFF phases

Inclusion of noncondensed pairs alters phase diagrams significantly

Abstract

We study the single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states for BCS--Bose-Einstein condensation (BEC) crossover at general temperatures $T$. Because we include the important effects of noncondensed pairs, our $T \neq 0$ phase diagrams are different from those reported in earlier work. We find that generalized LOFF phases may be the ground state for a wide range of (weak through moderately strong) interactions, including the unitary regime. However, these LOFF phases are readily destroyed by non-zero $T$.