Eur. Phys. J. B 78, 43-49 (2010)
https://doi.org/10.1140/epjb/e2010-10515-0

Phase diagram and deformed phase separation for a trapped Fermi gas with population imbalance and BCS pairing interaction

¹ SPIN-CNR, 84084 Fisciano (SA), Italy
² Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno, 84084 Fisciano (SA), Italy
³ Centre for Modern Physics, Chongqing University, Chongqing, 400044, P.R. China

Corresponding author: ^a canio@sa.infn.it

Received: 1 July 2010
Revised: 23 September 2010
Published online: 3 November 2010

Abstract

We study the phase separated state of an ultracold atomic Fermi gas confined in a three-dimensional quantum harmonic trap with a BCS pairing interaction. Examining various finite-temperature phase diagrams, we investigate the interplay between the filling of the quantum trap energy levels and the pairing energy. We find that a low (high) filling leads to a large (small) critical population imbalance for the superfluid/normal transition, together with a fully (partially) polarized normal part. We also show that the decrease of the density leads to a changeover of the shape of the superfluid core from an equipotential form to a deformed one. Moreover, we clarify the intrinsic mechanisms that lead to the deformation, providing a unified scenario for phase separation and deformation in a trapped Fermi gas, allowing for a possible interpretation of the apparently controversial experimental findings.