Superfluid phases of fermions with hybridized $s$ and $p$ orbitals

TL;DR

This paper investigates superfluid phases in a two-component Fermi system with hybridized s and p orbitals, revealing novel phase differences and complex behaviors driven by population imbalance, with implications for experimental realization.

Contribution

It introduces a mapping to the Lieb lattice and demonstrates the existence of a $\pi$-phase difference in superfluid order parameters due to s-p orbital hybridization.

Findings

Superfluid order parameters can have a $\pi$-phase difference between sites.

Population imbalance leads to various superfluid phases.

The predicted phenomena are observable in current experimental setups.

Abstract

We explore the superfluid phases of a two-component Fermi mixture with hybridized orbitals in optical lattices. We show that there exists a general mapping of this system to the Lieb lattice. By using simple multiband models with hopping between $s$ and $p$-orbital states, we show that superfluid order parameters can have a $\pi$-phase difference between lattice sites, which is distinct from the case with hopping between $s$-orbitals. If the population imbalance between the two spin species is tuned, the superfluid phase may evolve through various phases due to the interplay between hopping, interactions and imbalance. We show that the rich behavior is observable in experimentally realizable systems.