Interfacial Interactions Between High-Tc YBa2Cu3O7-x Thin Films and Substrates

Thin-film applications were immediately anticipated as the high-Tc superconductors were developed. Prior to the application of these films, however, a number of materials issues had to be investigated since the superconducting properties of these materials are strongly influenced by the microstructure. Individual microstructural features may be either beneficial or detrimental depending on their fine scale microstructure and distribution as well as on the specific application. A well-known example is the grain boundaries which can constitute weak links that limit the critical current density [1–3] but they can also be used in Josephson junction based devices [4–12]. Other defects may act as pinning centers that improve the critical current densities j c , but depending on their distribution and morphology they could also decrease the jc