Multi-particle instability in a spin-imbalanced Fermi gas

Abstract

Weak attractive interactions in a spin-imbalanced Fermi gas induce a multi-particle instability, binding multiple fermions together. The maximum binding energy per particle is achieved when the ratio of the number of up- and down-spin particles in the instability is equal to the ratio of the up- and down-spin densities of states in momentum at the Fermi surfaces, to utilize the variational freedom of all available momentum states. We derive this result using an analytical approach, and verify it using exact diagonalization. The multi-particle instability extends the Cooper pairing instability of balanced Fermi gases to the imbalanced case, and could form the basis of a many-body state, analogously to the construction of the Bardeen-Cooper-Schrieffer theory of superconductivity out of Cooper pairs.

11 pages, 6 figures, accepted for publication in Physical Review B

References in corpus (9)

• Calorimetric Evidence for a Fulde-Ferrell-Larkin-Ovchinnikov Superconducting State in the Layered Organic Superconductor κ$-(BEDT-TTF)$_2$Cu(NCS)$_2$
• Homogeneous Atomic Fermi Gases
• Phase diagram of a strongly interacting polarized Fermi gas in one dimension
• Pairing states of a polarized Fermi gas trapped in a one-dimensional optical lattice
• Evidence of Andreev bound states as a hallmark of the FFLO phase in $\kappa$-(BEDT-TTF)${}_2$Cu(NCS)${}_2$
• Quasi-one-dimensional polarized Fermi superfluids
• Exact Numerical Study of Pair Formation with Imbalanced Fermion Populations
• Polarized Fermi condensates with unequal masses: Tuning the tricritical point
• Zooming into the coexisting regime of ferromagnetism and superconductivity in ErRh4B4 single crystals

Cited by in corpus (3)

• Reentrant Fulde-Ferrell-Larkin-Ovchinnikov superfluidity in the honeycomb lattice
• Diffusion Monte Carlo study of a spin-imbalanced two-dimensional Fermi gas with attractive interactions
• Temporal fluctuation induced order in conventional superconductors