A Josephson junction (JJ) is a quantum mechanical device which is made of two superconducting electrodes separated by a barrier (thin insulating tunnel barrier, normal metal, semiconductor, ferromagnet, etc.).
The supercurrent Is through a Josephson junction is generally given by Is = Icsin(φ), where φ is the phase difference of the superconducting wave functions of the two electrodes, i.e. the Josephson phase.
[1] The critical current Ic is the maximum supercurrent that can exist through the Josephson junction.
From the above formula it is clear that the phase φ = arcsin(I/Ic), where I is the applied (super)current.
In certain cases, one may obtain a Josephson junction where the critical current is negative (Ic < 0).
For example, if one connects (shorts) the superconducting electrodes with the inductance L (e.g. superconducting wire), one may expect the spontaneous supercurrent circulating in the loop, passing through the junction and through inductance clockwise or counterclockwise.
Josephson junction was discussed in the context of heavy fermion p-wave superconductors.
[2] That work used a weak ferromagnet consisting of a copper-nickel alloy (CuxNi1−x, with x around 0.5) and optimized it so that the Curie temperature was close to the superconducting transition temperature of the superconducting niobium leads.