Spin and mass imbalance in a mixture of two species of fermionic atoms in a 1D optical lattice

TL;DR

This paper investigates how spin and mass imbalance affect phase transitions and pairing in a two-species fermionic mixture in a 1D optical lattice, revealing conditions favoring exotic superconducting states.

Contribution

It introduces a bosonization analysis of phase transitions and pairing behaviors considering both spin and mass imbalance in a 1D fermionic system.

Findings

Identification of two types of phase separation.

Existence of a quantum phase transition between phase-separated states.

Dominance of singlet superconducting correlations in the liquid phase.

Abstract

In this paper, we study the role of both "spin"(species) and mass imbalance in a mixture of two species of fermionic atoms with attractive interaction in an one-dimensional optical lattice. Using the bosonization approach, quantum phase transitions between a liquid phase and phase separated states are studied under various conditions of interaction, spin imbalance, and mass imbalance. We find that, in the phase-separated region, there exists two kinds of phase separation and a special quantum phase transition might exist between them in the large $U$ limit. On the other hand, the singlet superconducting correlation dominates in the liquid phase. The pairing behavior has been also demonstrated that there is oscillating behavior in real space. We find both the spin and mass imbalance are in favor of the formation of Fulde-Ferrell-Larkin-Ovchinnikov state.