Pairing of Fermions with Arbitrary Spin

TL;DR

This paper explores the superfluid states of optically trapped alkali fermions with high spin, analyzing the structure of large spin Cooper pairs and presenting an exact solution for J=2 pairing.

Contribution

It provides a detailed analysis of large spin Cooper pairs and an exact solution for J=2 pairing, revealing ground state changes with increasing fermion spin.

Findings

Large spin Cooper pairs have complex structures.

Exact solution for J=2 pairing shows ground state transitions.

Ground state properties vary with fermion spin.

Abstract

Motivated by the recent success of optical trapping of alkali Bose condensate, we have studied the superfluid state of optically trapped alkali fermions, which can have Cooper pairs with total spin $J\geq 2$. In this paper, we shall discuss the general structure of these large spin Cooper pairs and their close relation with singlet Cooper pairs with non-zero orbital angular momentum. We also present the exact solution for the J=2 pairing which shows a surprising change of ground state as the spin $f$ of the constituent fermion increases.