Anisotropic josephson effects in point contacts between the heavy fermion superconductor URu2Si2 and Nb

Abstract

Point contacts between the heavy-fermion superconductor URu2Si2 and Nb are studied. A finite dc Josephson current is found in contacts aligned parallel to the a-b directions of URu2Si2, whereas it is absent in contacts aligned along the c direction. We attribute this extreme anisotropy of the Josephson current to an unconventional superconducting order parameter in URu2Si2, with a symmetry leading to destructive interference for Josephson currents along the c direction. © 1998 The American Physical Society.