Superconducting superlattices: Verification of two-dimensional nature in high T c Bi2Sr2(Ca1−xYx)Cu2O8 superconductors

Abstract

An approach to evaluate the two‐dimensional nature in a high T_c superconductor is examined on the superconducting superlattice prepared by stacking of superconductor and nonsuperconductor layers. The Bi₂Sr₂(Ca_1−xY_x)₁Cu₂O₈‐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−xY_x)Cu₂O₈ high T_c superconductor.