INTEGRATED FERROELECTRIC AND SUPERCONDUCTOR CONCEPT FOR DEVICE APPLICATIONS

THE HIGH-TC SUPERCONDUCTOR BICASRCU-OXIDE AND THE FERROELECTRIC BI4TI3O12 HAVE A-, B-, AND C-LATTICE CONSTANTS THAT MATCH ALMOST EXACTLY. SINGLE CRYSTALS OF THEBI-FERROELECTRIC ARE AVAILABLE IN THE FORM OF LARGE THIN PLATES WHERE THE C-AXIS IS PERPENDICULAR TO THE PLATE, AND THIN/THICK FILMS OF THE BI-SUPERCONDUCTOR CAN BE GROWN BY LIQUID PHASE EPITAXY. THIS PROPOSAL DEALS WITH AN INTEGRATED FERROELECTRIC + SUPERCONDUCTOR STRUCTURE WHEREIN A FILM OF THE BI-SUPERCONDUCTOR IS GROWN ON A CRYSTAL PLATE OF THE BI-FERROELECTRIC. THE UTILITY OF THIS APPROACH IS THAT THE PIEZOELECTRIC STRESS INDUCED IN THE FERROELECTRIC PLATE BY AN APPLIED VOLTAGE IS USED TO ALTER THE PROPERTIES OF THE SUPERCONDUCTING FILM IN THE A-B PLANE FOR DEVICE APPLICATIONS. MEASUREMENTS OF THESE STRESS EFFECTS ON THE SUPERCONDUCTING TRANSITION TEMPERATURE AND CRITICAL CURRENT DENSITY ARE PROPOSED USING ACTUAL INTEGRATED STRUCTURES. MAGNETIC-FIELD EFFECTS ARE ALSO PROPOSED, AND ANISOTROPIC COUPLINGS WILL BE STUDIED (I.E., MAGNETIC FIELD PARALLEL AND PERPENDICULAR TO THE CURRENT DIRECTION IN THE FILM). ITIS ALSO PROPOSED TO EVALUATE VARIOUS DEVICE APPLICATIONS SUGGESTED BY THE MEASUREMENTS.