  The superfluid transition in an ultracold two-component atomic Fermi gas is
analyzed in the case where the two components have different densities. We
describe a superfluid state which spontaneously breaks the rotational-symmetry
by deforming the Fermi surfaces of both species into ellipsoidal form. At
relatively large hyperfine-spin asymmetries, this deformation is shown to help
the appearance of pairing, which in the rotationally-symmetric (BCS) case would
be forbidden by Pauli blocking. The prospects for experimental detection of
such a deformed Fermi surface phase are discussed.
