Fabrication of Josephson junctions on La-Sr-Cu-O single crystals

We have successfully fabricated Josephson junctions on single crystals of La/sub 2-x/Sr/sub x/CuO/sub 4/ (LSCO) high-T/sub c/ superconductor using niobium (Nb) as counter electrodes. A reproducible fabrication process has been established taking into account the surface state of LSCO is dominantly affecting junction properties. The surface state of LSCO has been characterized using XPS. The current voltage curves (IVCs) of Nb/LSCO junctions exhibit RSJ like Josephson junction properties. Due to intrinsic Josephson effect of LSCO, the IVCs branches are first observed for the Nb/LSCO junctions on LSCO mesa whose interfaces are parallel to the ab-plane of LSCO.