| 摘要 |
PURPOSE:To increase the upper limit of a vortex driving current flowing in a grounding thin film and to remove vortexes from the central part of the grounding thin film, by providing a superconductive thin film comprising a material different from the grounding thin film in a region, in which a circuit is provided at least one part of the grounding thin film in a region, where a Josephson circuit is not provided. CONSTITUTION:In a grounding thin film 1 in a region 11 wherein Josephson circuits are distributed, it is ideal to have a pinning forces 10 as follows: a weak pinning force in the Josephson circuit so that vortexes can be removed as easily as possible; and a large pinning force at the peripheral part of the grounding thin film 1 so that the newly formed vortexes are not moved. In order to realize these factors, the central part of the grounding thin film and its peripheral part are constituted with different superconductive metal materials. In general, when a current density is increased too much, a magnetic field higher than a superconductive critical magnetic field is generated at the peripheral part of a superconductive thin film, which is in parallel with a current in the thin film. Therefore an ideal vortex driving current J becomes JC>J> JF. When the grounding thin film having such a structure is used, the vortex can be normally removed from the central part of the grounding thin film even at a current density of JPE>J>JC>JP or JPE>J>HP>JC (a).
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