Layered superconductors as one-dimensional Josephson arrays

The large anisotropy and the extremely short coherence lengths of the high-T-c superconductors suggest that the layered crystal structure is mapped onto a periodic modulation of the superconducting order parameter. Even ideal high-T-c single crystals consist of a stacked series of superconducting and non-superconducting layers. As the typical interlayer distance is approximately 15 Angstrom, a single crystal of 3 mu m thickness should behave like a stack of 2000 Josephson junctions. In order to access these atomic scale devices, vertical structures on single crystal surfaces and epitaxial thin films were fabricated. We present results of mesa structures and vertical step-edges.