High T_c Superconducting Layered Structures and Superlattices

Abstract

In this talk I will discuss the Bellcore/Rutgers effort in the area of artificially structured high T_c superconductors of YBa₂Cu₃O_7−x intercalated with semiinsulating layers of PrBa₂Cu₃O_7−x. Such structures could be the building blocks for future Josephson Junction devices. We have used these superlattices to study the effect of coupling between Cu-O planes in the high-T_c superconductors. Superconductivity was found when YBaCu₃O_7−x, layers were as thin as 12 Å. The transition temperature T_c increased monotonically to the bulk value with increasing YBa₂Cu₃O_7−x, layer thickness and also increased when the PrBa₂Cu₃O_7−x, layer was thin which we attribute to increased coupling between adjacent layers of YBa₂Cu₃O_7−x,. The sheet resistance at which T_c begins to fall substantially is approximately ħ/e², in striking similarity to the behavior of ordinary superconducting thin films.