Josephson junction in a wiring pattern of a superconductor oxide

摘要

A Josephson junction is disclosed which includes a substrate of a single crystal having a substantially flat surface, a wiring pattern of an oxide superconductor formed on the flat surface of the substrate, and an altered region formed having a width of 300 nm or less and formed in the wiring pattern to intersect the wiring pattern, the crystal orientations of the wiring pattern on both sides of the altered region being equal to each other. The Josephson junction may be prepared by a process including the steps of: (a) coating a surface of a substrate of a single crystal with a normal metal to form a protecting layer over the surface of the substrate; (b) irradiating a predetermined portion of the protecting layer with a focused ion beam so that an irradiated portion is formed in the substrate; (c) removing the protecting layer from the substrate; and (d) forming a wiring pattern of an oxide superconductor on the surface of the substrate from which the protecting layer has been removed such that the wiring pattern crosses the irradiated portion of the substrate, thereby forming an altered portion in the wiring pattern at a position above the irradiated portion.