Deformation of a Trapped Fermi Gas with Unequal Spin Populations
G. B. Partridge, Wenhui Li, Y. A. Liao, R. G. Hulet, M. Haque, H. T. C. Stoof
Abstract
The real-space densities of a polarized strongly-interacting two-component Fermi gas of
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Li 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.