Multilayer Nb-Ti for Use as Model Superconducting Microstructures

Thin film deposition techniques provide opportunities to control the microstructure of two-phase alloy superconductors more completely than that possible by conventional metallurgical processing. We have fabricated thin film multilayer structures based on Nb-Ti alloy superconductors. The goal is to provide model microstructures that can be easily compared to flux-pinning theories of high-critical-current superconductivity. In this study, multilayer Nb/Ti materials have been annealed to provide samples with a variety of superconducting / normal interfaces, ranging from atomically sharp interfaces to heavily inter-diffused interfaces. Measurements of electrical and microstructural properties are described and compared with model predictions from proximity coupling theory and alloy diffusion.