Fabrication and characteristics of artificial SNS junctions using three axes orientation-controlled α-axis oriented Y123/Pr123 multilayer films

Artificial superconductor/ normal conductor/ superconductor (SNS) junctions are fabricated using a-axis oriented films. The films are three axes orientation-controlled a-axis oriented YBa₂Cu₃O _7-y/PrBa₂Cu₃O_7-y alternately-layered thin films (Y123/Pr123 multilayer films). The multilayer films were grown by a pulsed laser deposition method using a sintered Y123 target with a Pr123 section. The dark contrast parallel to the substrate surface (bc-plane), which corresponds to the elemental distribution of Pr, are observed periodically in the transmission electron microscopic cross-sectional image. SNS junctions along a-axis were fabricated using the multilayer films by focused-ion-beam techniques. Nonlinear current-voltage curves with the critical current of ∼5×10^-7 A were obtained at 30 K for a fabricated junction with the area of ∼0.2×0.2 μm².