Coexistence of density wave and superfluid order in a dipolar Fermi gas

TL;DR

This paper explores the coexistence of superfluidity and density wave order in a dipolar Fermi gas, revealing a stable supersolid phase with p-wave pairing driven by anisotropic dipolar interactions.

Contribution

It demonstrates the conditions under which superfluid and density wave orders coexist in a dipolar Fermi gas, highlighting the role of anisotropic interactions in stabilizing a supersolid phase.

Findings

Coexistence of superfluid and density wave order in dipolar Fermi gases.

Identification of a stable supersolid phase with p-wave pairing.

Proposal for detecting the supersolid phase via time-of-flight experiments.

Abstract

We analyse the coexistence of superfluid and density wave (stripe) order in a quasi-two-dimensional gas of dipolar fermions aligned by an external field. Remarkably, the anisotropic nature of the dipolar interaction allows for such a coexistence in a large region of the zero temperature phase diagram. In this region, the repulsive part of the interaction drives the stripe formation and the attractive part induces the pairing, resulting in a supersolid with $p$-wave Cooper pairs aligned along the stripes. From a momentum space perspective, the stability of the supersolid phase is due to the fact that the stripe order renders the Fermi surface only partially gapped, leaving gapless regions that are most important for $p$-wave pairing. We finally demonstrate how this supersolid phase can be detected in time-of-flight experiments.