Impact of the symmetry of the superconducting wave function on supercurrent transport in YBa₂Cu₃O_7-δ josephson junctions

Abstract

We report tunneling measurements on specially designed YBa2Cu3O7-δ bicrystal Josephson junctions. A strong anisotropy in the characteristic voltage IcRn of the Josephson junctions in the a-b plane was observed. The theoretical analysis shows that the tunneling can be explained as combined effect of the presence of nodes in the superconducting wave function, either generalized s-wave with 8 nodes or dx2-y2-wave, and strong anisotropy of the tunneling matrix elements.