Fulde-Ferrell--Larkin-Ovchinnikov state in the dimensional crossover between one- and three-dimensional lattices

TL;DR

This paper maps the phase diagram of the FFLO state in a 3D-coupled chain Hubbard model, revealing how dimensional crossover influences stability and shell structure, with implications for ultracold atomic gases.

Contribution

It provides the first comprehensive phase diagram of the FFLO state across 1D to 3D crossover using real-space dynamical mean-field theory.

Findings

Dimensionality significantly affects shell structure in the FFLO state.

Optimal intermediate interchain coupling extends FFLO stability.

Mixed 1D-3D FFLO states are more thermally robust.

Abstract

We present a full phase diagram for the one-dimensional (1D) to three-dimensional (3D) crossover of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in an attractive Hubbard model of 3D-coupled chains in a har- monic trap. We employ real-space dynamical mean-field theory which describes full local quantum fluctuations beyond the usual mean-field and local density approximation. We find strong dimensionality effects on the shell structure undergoing a crossover between distinctive quasi-1D and quasi-3D regimes. We predict an optimal regime for the FFLO state that is considerably extended to intermediate interchain couplings and polarizations, directly realizable with ultracold atomic gases. We find that the 1D-like FFLO feature is vulnerable to thermal fluctuations, while the FFLO state of mixed 1D-3D character can be stabilized at a higher temperature.