Imbalanced ultracold Fermi gas in the weakly repulsive regime: Renormalization group approach for p-wave superfluidity

TL;DR

This paper investigates a novel p-wave superfluid pairing mechanism in a two-dimensional imbalanced Fermi gas with repulsive interactions, using a renormalization group approach to predict superfluid instability and transition temperature.

Contribution

It introduces a renormalization group method to analyze p-wave superfluidity in imbalanced Fermi gases, revealing effective attraction induced by particle-hole susceptibility.

Findings

Superfluid instability occurs in the p-wave channel for the majority species.

Effective attraction is mediated by the minority species' particle-hole susceptibility.

The Fermi surface mismatch influences the pairing mechanism.

Abstract

We theoretically study a possible new pairing mechanism for a two-dimensional population imbalanced Fermi gas with short-range repulsive interactions which can be realized on the upper branch of a Feshbach resonance. We use a well-controlled renormalization group approach, which allows an unbiased study of the instabilities of imbalanced Fermi liquid without assumption of a broken symmetry and gives a numerical calculation of the transition temperature from microscopic parameters. Our results show a leading superfluid instability in the p-wave channel for the majority species. The corresponding mechanism is that there are effective attractive interactions for the majority species, induced by the particle-hole susceptibility of the minority species, where the mismatch of the Fermi surfaces of the two species plays an important role. We also propose an experimental protocol for detecting the p-wave superfluidity and discuss the corresponding experimental signatures.