Pairing from repulsion in a two-dimensional Fermi gas with soft-core interactions

Abstract

We investigate a model many-body system of spinless Fermi gas in two dimensions, where the bare two-body interaction is repulsive and takes the form of a soft-core disk potential. We obtain the zero temperature phase diagram of this model by numerical functional renormalization group (FRG), which retains the effective interaction vertices in all channels to provide a detailed picture of how Cooper pairing emerges under the renormalization flow. The repulsion drives the system to a series of superfluid states with higher angular momentum paring, for example in the $f$- and $h$-wave channels instead of the $p$-wave channel. This is in sharp contrast to the original Kohn-Luttinger mechanism where pairing of very large angular momenta and exponentially small transition temperature was predicted. We trace the stabilization and enhancement of $f$- and $h$-wave pairing back to the momentum dependence of the bare interaction. A perturbative calculation is carried out to show that while the second order Kohn-Luttinger diagrams provide a qualitative understanding of the onsets of the various superfluid phases, they are unable to accurately capture the phase boundaries predicted by FRG. Our findings suggest that tuning the shape of the interaction potential offers a promising route to achieve stronger ``pairing glue" and to realize nontrivial superfluid phases in repulsive Fermi gases beyond the scope of the original Kohn-Luttinger analysis.

arXiv commentPublished version, with updated title, abstract, and introduction

References in corpus (22)

• Renormalization Group Approach to Interacting Fermions
• Functional renormalization group approach to correlated fermion systems
• Tuning p-wave interactions in an ultracold Fermi gas of atoms
• P-wave Feshbach resonances of ultra-cold ${}^6$Li
• p-Wave Interactions in Low-Dimensional Fermionic gases
• Evidence for universal relations describing a gas with $p$-wave interactions
• Quench Dynamics of a Fermi Gas with Strong Non-Local Interactions
• Effects of longer-range interactions on unconventional superconductivity
• Exotic topological density waves in cold atomic Rydberg fermions
• Unconventional high-temperature superconductivity from repulsive interactions: theoretical constraints
• Bond order solid of two-dimensional dipolar fermions
• Collisional loss of one-dimensional fermions near a $p$-wave Feshbach resonance
• Two-body relaxation in a Fermi gas at a p-wave Feshbach resonance
• Observation of unitary p-wave interactions between fermions in an optical lattice
• Quantum phases of quadrupolar Fermi gases in optical lattices
• $F$-wave pairing of cold atoms in optical lattices
• P-wave Superfluidity by Blockade Effects in a Rydberg-Dressed Fermi Gas
• Collective Modes and f-wave Pairing Interactions in Superfluid 3He
• Unconventional Spin Density Waves in Dipolar Fermi Gases
• $f$-wave superfluidity from repulsive interaction in Rydberg-dressed Fermi gas
• Competing many-body instabilities in two-dimensional dipolar Fermi gases
• Multipolar Fermi-surface deformation in a Rydberg-dressed Fermi gas with long-range anisotropic interactions