Rotating Larkin-Ovchinnikov-Fulde-Ferrell state of the two-dimensional ultracold Fermi superfluid gas: Reentrant behavior of the critical angular velocity

A rotating ultracold S-wave superfluid Fermi gas is studied when the mismatch in chemical potentials δμ (and the population imbalance δn) corresponds to the Larkin-Ovchinnikov-Fulde-Ferrell state in the vicinity of the Lifshitz critical point. It is shown that under these conditions the critical angular velocity Ωc2 in two-dimensional systems is an oscillating function of temperature and δn giving rise to reentrant superfluid phases. The reason for this behavior is the population by Cooper pairs of the Landau levels (n≥1) above the lowest one (n=0).