Feasibility of a Fulde-Ferrell-Larkin-Ovchinnikov superfluid Fermi atomic gas

Abstract

We theoretically explore a promising route to achieve the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in a spin-imbalanced ultracold Fermi gas. In the current stage of cold atom physics, search for this exotic Fermi superfluid is facing two serious difficulties: One is the desperate destruction of the FFLO long-range order by FFLO pairing fluctuations, which precludes entering the phase through a second-order transition, even in three dimension. The other is the fierce competition with the phase separation into the BCS (Bardeen-Cooper-Schrieffer) state and the spin-polarized normal state. Including strong FFLO pairing fluctuations within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we show that the anisotropy of Fermi surface introduced by an optical lattice makes the FFLO state stable against the paring fluctuations. This stabilized FFLO state is also found to be able to overcome the competition with the phase separation under a certain condition. Since the realization of unconventional Fermi superfluids is one of the most exciting challenges in cold atom physics, our results would contribute to the further development of this field.

15 pages, 9 figures

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• Stability of the Fulde-Ferrell-Larkin-Ovchinnikov states in anisotropic systems and critical behavior at thermal $m$-axial Lifshitz points
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Cited by in corpus (9)

• Unconventional superconductivity of an altermagnetic metal: Polarized BCS and inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov states
• Stable non-equilibrium Fulde-Ferrell-Larkin-Ovchinnikov state in a spin-imbalanced driven-dissipative Fermi gas loaded on a three-dimensional cubic optical lattice
• Nonequilibrium BCS-BEC crossover and unconventional FFLO superfluid in a strongly interacting driven-dissipative Fermi gas
• Engineering nonequilibrium superconducting phases in a voltage-driven superconductor under an external magnetic field
• Pairing properties of an odd-frequency superfluid Fermi gas
• Multiple polaron quasiparticles with dipolar fermions in a bilayer geometry
• Novel dynamical excitations and roton-based measurement of Cooper-pair momentum in a two-dimensional Fulde-Ferrell-Larkin-Ovchinnikov superfluid on optical lattices
• Structures and proximity effects of inhomogeneous population-imbalanced Fermi gases with pairing interactions
• Emergence of Charge-Imbalanced BCS State and Suppression of Nonequilibrium FFLO State in Asymmetric NSN Junctions