High-Temperature Atomic Superfluidity in Lattice Bose-Fermi Mixtures

Abstract

We consider atomic Bose-Fermi mixtures in optical lattices and study the superfluidity of fermionic atoms due to $s$-wave pairing induced by boson-fermion interactions. We prove that the induced fermion-fermion coupling is always attractive if the boson-boson on-site interaction is repulsive, and predict the existence of an enhanced BEC-BCS crossover as the strength of the lattice potential is varied. We show that for direct on-site fermion-fermion repulsion, the induced attraction can give rise to superfluidity via $s$-wave pairing at striking variance with the case of pure systems of fermionic atoms with direct repulsive interactions.