JPS6415988A - Superconducting device - Google Patents

Abstract

PURPOSE:To obtain a superconducting device having weak coupling Josephson characteristics, by a method wherein a small critical current region is locally formed only by arranging a thin wire in (c) axial flow direction, by utilizing anisotropy in oxide superconducting crystal such as K2NiF4 structure. CONSTITUTION:A superconducting single crystal thin film 1 is composed of a material having, e.g., layer-type perovskite structure (K2NiF4 structure), and can be formed on, e.g., a strontium titanate 110 orientation substrate 4, by a means such as sputtering, electron beam deposition method, and MOVPE method. In the single crystal film formed in this manner, anisotropy appears in critical current density when a current is made to flow either in the (c) axis direction, or in the perpendicular direction to the (c) axis. In the part JJ where the current flows in the (c) axis direction, the critical current value is small, so that, even in the case of small current value, the superconductivity is easily weakened together with the action of self magnetic field, and a phase difference generates between electrodes 2 and 3. As the result, weak coupling Josephson characteristics can be obtained, wherein voltage transition occurs at a constant threshold value as a boundary, in the same manner as usual devices.