New Phases and Angular Momentum of Rotating Chiral p-Wave Superfluids Confined in an Annulus

Persistent mass currents of a chiral p-wave superfluid confined in a toroidal annulus stabilize new equilibrium states. We present theoretical calculations of the corresponding phase diagram, the internal structure of the superfluid order parameter, and the angular momentum based on the Ginzburg-Landau free energy functional for ³He. For sufficiently small persistent current the angular momentum of the chiral phase is quantized in integer units given by the winding number of the global phase. These low-flow states can be stabilized by rotating the annulus at certain critical angular velocities. As the winding number is increased an asymmetry between the edge currents on the inner and outer radius develops, and at the critical value of the persistent current the superfluid undergoes a transition to a spatially inhomogeneous axial domain wall phase. We show that this phase is energetically favored at sufficiently large persistent current, with both the edge and domain wall currents counter-propagating relative to the bulk supercurrent. The axial domain wall state is also metastable down to zero bulk flow and exhibits a significantly increased angular momentum compared with the stable chiral ground state. This anomaly in the angular momentum is a direct signature of the axial domain wall phase of the superfluid condensate.