title: Deformation of a trapped Fermi gas with unequal spin populations.
abstract: The real-space densities of a polarized strongly interacting two-component Fermi gas of 6Li atoms reveal two low-temperature regimes, both with a fully paired core. At the lowest temperatures, the unpolarized core deforms with increasing polarization. Sharp boundaries between the core and the excess unpaired atoms are consistent with a phase separation driven by a first-order phase transition. In contrast, at higher temperatures the core does not deform but remains unpolarized up to a critical polarization. The boundaries are not sharp in this case, indicating a partially polarized shell between the core and the unpaired atoms. The temperature dependence is consistent with a tricritical point in the phase diagram.
authors.affiliation: Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, TX 77251, USA.
authors.forename: G B
authors.initials: GB
authors.lastname: Partridge
authors.forename: Wenhui
authors.initials: W
authors.lastname: Li
authors.forename: Y A
authors.initials: YA
authors.lastname: Liao
authors.forename: R G
authors.initials: RG
authors.lastname: Hulet
authors.forename: M
authors.initials: M
authors.lastname: Haque
authors.forename: H T C
authors.initials: HT
authors.lastname: Stoof