Spin-orbit Coupling Effects on the Superfluidity of Fermi Gas in an Optical Lattice

Abstract

We investigate the superfluidity of attractive Fermi gas in a square optical lattice with spin-orbit coupling (SOC). We show that the system displays a variety of new filling-dependent features. At half filling, a quantum phase transition from a semimetal to a superfluid is found for large SOC. Close to half filling where the emerging Dirac cones governs the behaviors of the system, SOC tends to suppress the BCS superfluidity. Conversely, SOC can significantly enhance both the pairing gap and condensate fraction and lead to a new BCS-BEC crossover for small fillings. Moreover, we demonstrate that the superfluid fraction also exhibits many interesting phenomena compared with the spin-orbit coupled Fermi gas without lattice.

references updated and typos corrected

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• The Pairing of Spin-orbit Coupled Fermi Gas in Optical Lattice
• Spin-orbit-coupled atomic Fermi gases in two-dimensional optical lattices in the presence of a Zeeman field
• Helical currents in metallic Rashba strips
• Multiorder topological superfluid phase transitions in a two-dimensional optical superlattice
• A numerically exact study of Weyl superconductivity
• Phase diagram, band structure and density of states in two-dimensional attractive Fermi-Hubbard model with Rashba spin-orbit coupling
• Nature of the mixed-parity pairing of attractive fermions with spin-orbit coupling in optical lattice
• Bloch bound state of spin-orbit-coupled fermions in an optical lattice
• Anderson Localization in Degenerate Spin-Orbit Coupled Fermi Gases with Disorder
• Spin Excitation Spectra of Spin-Orbit Coupled Bosons in Optical Lattice