Elastic theory of Normal-Superfluid Boundary in trapped Fermi Gases

By modeling the normal-superfluid boundary in a trapped polarized Fermi gas as an elastic membrane, we calculate the atomic density profile. For small trapping anisotropy, we find that the superfluid-normal boundary remains approximately elliptical, and has an aspect ratio different from that of the trap. For very prolate clouds the boundary becomes distorted into a capsule-like shape. We present an analytic explanation of this shape.