Functional decoupling of nanostructured areas in superconducting strips for electromagnetic detectors

We studied high temperature superconducting devices created by means of local nanostructuring with high-energy heavy-ion lithography. Linear arrays of alternate nanostructured and as-grown YBa2Cu3O7-x film regions are patterned on the microscale. The density of the induced nanostructures is tuned in such a way to locally depress the superconducting properties until a functional electromagnetic decoupling between nanostructured and as-grown microzones is achieved in suitable regions of the (B, T) phase diagram. Pilot prototypes engineered for operating as magnetic field detectors in harsh cryogenic environment are characterized by electric transport and surface morphology analysis at microscale and nanoscale. Sensitivity, linearity range, and bandwidth limits of the pilot prototype are established from electrical transport characterization. The morphological analysis reveals the salient aspects of the surface modifications occurring with high-fluence heavy-ion lithography. Radiation annealing experiments with 3.5 MeV proton energy were performed to check out the reliability of the prototype operating in harsh environments. These measurements demonstrate the robustness of this approach aimed at creating dissipative microscale units that are sensitive to magnetic fields in a continuous dissipationless superconducting material. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2982370]