Breached superfluidity of fermionic atoms in magnetic field

Abstract

We derived the energy gap of a breached pairing superfluidity phase of fermionic atoms in an external magnetic field in Feshbach resonance experiments which is determined by the magnetic - field detuning from the Feshbach resonance. We show that a BCS superfluid state exists only for the magnetic - field detuning smaller than one critical, and this critical magnetic - field detuning is determined by the equality of the Zeeman energy splitting for the magnetic - field detuning to the energy gap $ \Delta_0 $.