Fulde-Ferrel-Larkin-Ovchinnikov phase in one dimensional Fermi gas with attractive interactions and transverse spin-orbit coupling

TL;DR

This paper investigates the FFLO phase in a one-dimensional attractive Fermi gas with spin-orbit coupling and Zeeman field, revealing how SOC influences phase transitions and phase stability.

Contribution

It provides a comprehensive phase diagram showing the effects of spin-orbit coupling on the FFLO phase and phase transitions in a 1D Fermi gas with attractive interactions.

Findings

FFLO phase exists with attractive interactions and Zeeman field

SOC suppresses FFLO order and promotes pair formation

Transition from BCS to FFLO becomes continuous with SOC

Abstract

We examine the existence and characteristics of the exotic Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase in a one-dimensional Fermi gas with attractive Hubbard interactions, in the presence of spin-orbit coupling (SOC) and Zeeman field. We show that a robust FFLO phase can be created in the presence of attractive on-site interactions and Zeeman field, and that the addition of SOC suppresses the FFLO order and enhances the pair formation. In absence of SOC, the system shows four phases: Bardeen-Cooper-Schrieffer (BCS), FFLO, multi- mode pairing and fully polarized phases by tuning the Zeeman field h, and the quantum transition between these phases is discontinuous with respect to h. In the presence of SOC, the transition from the BCS to FFLO phase becomes continuous. We present a complete phase diagram of this model both in the presence and in the absence of SOC at quarter electron filling and also explore the effect of SOC on the FFLO phase.