Instability of Superfluid across Feshbach Resonances

We consider a dilute atomic gas comprising two species of Fermions with unequal concentrations. We study at zero temperature the atom‐molecule mixture with inter‐species low‐energy scatterings induced by a Feshbach resonance. To examine the stability of this superfluid, we calculate the chemical potential and the superfluid density for fixed individual concentrations. We find that the system can have distinct properties compared to the ordinary Bose‐Fermi mixture due to the unbound fermions.