Mesoscopic fluctuations of Josephson current in high-Tc superconductor junctions

The dc Josephson current and its fluctuations in superconductor/dirty normal metal/superconductor junctions are studied numerically by using the recursive Green function method, where a d-wave pairing symmetry is assumed in superconductors as it is in high-Tc materials. The Josephson current is sensitive to the orientation angle (α) between the crystalline axis of the high-Tc superconductors and the normal of the junction interface. When the orientation angle is π/4, the fluctuations of the Josephson current become larger than those with α=0 because of the zero-energy state formed at junction interfaces