Fulde-Ferrell-Larkin-Ovchinnikov phase in the presence of pair hopping interaction

TL;DR

This paper explores how pair hopping interactions influence the formation and characteristics of the FFLO superconducting phase, revealing possible coexistence with eta-pairing and implications for experimental observations.

Contribution

It introduces a model incorporating pair hopping interactions that induce FFLO phases with distinct modulations and coexistence with eta-pairing, advancing understanding of unconventional superconductivity.

Findings

Magnetic field can induce different FFLO modulations depending on pair hopping strength.

Eta-pairing can coexist with d-wave superconductivity within the FFLO phase.

Properties of the FFLO phase can reveal the magnitude of pair hopping interactions.

Abstract

The recent experimental support for the presence of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase in the CeCoIn5 directed the attention towards the mechanisms responsible for this type of superconductivity. We investigate the FFLO state in a model where on--site/inter--site pairing coexists with repulsive pair hopping interaction. The latter interaction is interesting in that it leads to pairing with nonzero momentum of the Cooper pairs even in the absence of the external magnetic field (the so-called eta-pairing). It turns out that depending on the strength of the pair hopping interaction the magnetic field can induce one of two types of the FFLO phase with different spatial modulations of the order parameter. It is argued that the properties of the FFLO phase may give information about the magnitude of the pair hopping interaction. We also show that eta-pairing and d-wave superconductivity may coexist in the FFLO state. It holds true also for superconductors which in the absence of magnetic field are of pure d-wave type.