Josephson effects in unconventional heavy fermion superconductors
We discuss the Josephson effect for pairing states which break crystal symmetries in addition to gauge symmetry. We consider theE 1g andE 2u models for the low-temperature phase ofUPt 3, with order parameters Δ(E 1g )∼p z (p x +ip y ) and Δ(E 2u )∼p z (p x +ip y )2. We report calculations of Josephson critical currents, taking into account the effects of depairing at the interface. For singlet-triplet junctions the critical current is non-zero only for spin-orbit, spin-flip tunneling, and is found to be much smaller than the Ambegaokar-Baratoff value even when the spin-orbit tunneling amplitude is comparable to the spin-independent amplitude.
KeywordsCritical Current Tunnel Junction Josephson Current Orbital Symmetry Unconventional Superconductor