Effect of the surface tension on the shape of the superfluid region in population imbalanced unitary Fermi gases.

We use a variational approach to determine the shape of the central superfluid shell of apopulation imbalanced unitary Fermi gases. We find that the surface tension between superfluid and normal regions significantly distorts the superfluid shell from an ellipsoidal shape to a cylindrical shape as experimentally seen in highly anisotropic traps. Comparing with experimental data, we find that the surface tension has strong temperature dependence and this allows us to compare the temperatures of various available experiments.