Physical Properties of the High-Tc Oxide Superconductors

摘要

Under this contract, thin film deposition technology suitable for in situdeposition of the high temperature superconductor YBa2Cu3O7 was developed and the materials science of the resulting films examined. The important role of cation disorder was identified. The composition dependence of the superconducting properties of the films near stoichiometry was characterized, providing critical information on the degree of composition control needed. In addition, amorphous silicon tunnel barriers were used to study the role of localized states on transport through tunnel barriers. The importance of directed chains of localized states in this process was definitively proven and compared with theory. The correlated nature of such tunneling was also demonstrated. A deleterious effect of localized states on Josephson tunneling was documented.