Fermion Superfluids of Non-Zero Orbital Angular Momentum near Resonance

TL;DR

This paper investigates non-zero angular momentum fermion superfluids near resonance, revealing their orbital ferromagnetic ground states and how their pairing symmetry influences observable properties.

Contribution

It provides an analytic solution to the gap equation for higher angular momentum superfluids and characterizes their ground states and degeneracies.

Findings

Ground states are orbital ferromagnets with specific pairing symmetries.

Degeneracy exists between different pairing states for bcl=2.

Angular momentum orientation is influenced by dipole energy.

Abstract

We study the pairing of Fermi gases near the scattering resonance of the $\ell\neq 0$ partial wave. Using a model potential which reproduces the actual two-body low energy scattering amplitude, we have obtained an analytic solution of the gap equation. We show that the ground state of $\ell=1$ and $\ell=3$ superfluid are orbital ferromagnets with pairing wavefunctions $Y_{11}$ and $Y_{32}$ respectively. For $\ell=2$, there is a degeneracy between $Y_{22}$ and a "cyclic state". Dipole energy will orient the angular momentum axis. The gap function can be determined by the angular dependence of the momentum distribution of the fermions.