Impact of the symmetry of the superconducting wave function on Josephson tunneling in high-T_c superconductors

摘要

We have designed an experiment where the Josephson barrier, in our case the misorientation angle of a bicrystal grain boundary, is kept constant, while the direction of the superconducting wave function at the barrier varies. The Josephson current in these junctions is strongly anisotroptc. The characteristic voltage I_cR_n depends on the crystal orientation related to the grain boundary. A theoretical analysis shows that this may be explained as a combined effect of nodes in the gap function and anisotropy of the tunneling matrix elements.