SUPERCONDUCTING SUPERLATTICES - VERIFICATION OF 2-DIMENSIONAL NATURE IN HIGH-TC BI2SR2(CA1-XYX)CU2O8 SUPERCONDUCTORS

An approach to evaluate the two-dimensional nature in a high Tc superconductor is examined on the superconducting superlattice prepared by stacking of superconductor and nonsuperconductor layers. The Bi 2Sr2(Ca1-xYx)1Cu 2O8-based superlattices have been formed by stacking two different unit cell layers containing different yttrium concentrations. One unit layer contains lower yttrium concentration (x=0.15) to be a superconductor, and the other contains higher concentration (x=0.5) to be a semiconductor, and these layers are periodically stacked with appropriate ratios. These superlattices exhibit the same resistance-temperature curve as the original superconducting films with x=0.15. This behavior can be explained by the strong two-dimensional character in this Bi2Sr2(Ca 1-xYx)Cu2O8 high Tc superconductor.