BCS pairing in fully repulsive fermion mixtures

TL;DR

This paper demonstrates that in a mixture of two repulsively interacting fermion gases, effective attraction can emerge via collective excitations, leading to BCS pairing despite the repulsive interactions.

Contribution

It reveals a novel mechanism where collective excitations induce effective attraction, enabling BCS pairing in purely repulsive fermion mixtures.

Findings

Effective attraction arises from collective excitations.

BCS pairing occurs despite initial repulsive interactions.

Parameter space conditions for pairing are identified.

Abstract

We consider a mixture of two neutral cold Fermi gases with repulsive interactions. We show that in some region of the parameter space of the system the effective attraction between fermions of the same type can appear due to the exchange of collective excitations. This leads to the formation of BCS pairing in the case where bare inter-atomic interactions are repulsive.