MAGNETIC SCREENING IN PROXIMITY-COUPLED SUPERCONDUCTOR NORMAL-METAL BILAYERS

The electrodynamics of a metallic surface layer in proximity contact to a superconductor are considered. The surface region is modeled as an idealized proximity-coupled superconductor/normal-metal (S/N) bilayer. Analytical expressions for the magnetic-field penetration into the sample are obtained. The behavior of the model and its applicability to magnetic-screening-length measurements on artificial and naturally occurring S/N bilayer superconductors are discussed in various limits. Calculations of the effective penetration depth eff(T) reveal that unconventional penetration depth temperature dependences, such as eff(T)T found in YBa2Cu3O7- crystals, are qualitatively reproduced with this model. © 1994 The American Physical Society.