ATOMIC-LAYER FABRICATION OF HIGH-T-C TUNNEL-JUNCTIONS

Using ALL-MBE, we have engineered a novel, metastable cuprate supercon ductor, BiSr2Ca7-xDyxCu8O19+y, in which only the central Ca layer is d oped by Dy. This provides, within a single unit cell, the bottom super conducting electrode, an insulating barrier layer (only few Angstrom t hick), and the top superconducting electrode, thus constituting an art ificial intra-cell Josephson junction. In this way, we have fabricated the first high-T-c tunnel (SIS) junctions. They exhibit very sharp qu asiparticle tunneling I-V characteristics, consistent with tunneling b etween 2D superconductors with d-wave pairing.