pi states in Josephson Junction between He-3-B

Abstract

We investigate the dependence of the current-phase relationship on the orientation of the order parameter for a pinhole between two $^3$He-B reservoirs. We show that, due to the internal spin structure of the superfluid, the energy of the junction may have a relative minimum at phase difference equals $\pi$ at low temperatures. The dependence of the supercurrent on the direction of an applied magnetic field can be used to verify the present mechanism for the ``$\pi$-states''.