Phase diagram for the trapped p-wave fermionic superfluid with population imbalance

摘要

We consider the problem of spin-triplet p-wave superfluid pairing with total spin projection m_s = 0 in atomicFermi gas across the Feshbach resonance.We allow for imbalanced populations and take into account the effectsdue to the presence of a harmonic trapping potential. Within the mean-field approximation for the one- andtwo-channel pairing models we show that the p-wave superfluid state has the lowest energy up to some distancefrom the trap center, the distance depending on population imbalance and the side of the Feshbach resonance(BCS or BEC) the system is in. Beyond this, the system is in the normal state. Since the system, even in thepresence of the harmonic trap, is invariant under O(3) space rotation, the superfluid cores which emerge in thetrap are comprised of states that are degenerate with respect to the “orbital ferromagnet” state, p_x ± ip_y, aswell as the ones in which all angular momentum components of the order parameter are nonzero, provided themodulus of the order parameter maintains a fixed magnitude.