| 摘要 |
A superconducting quantum interference device is provided which can accurately measure only a magnetic field detected by a detection coil where the superconducting quantum interference device is used for a fluxmeter. A superconductor for enclosing a loop to be formed by a washer coil is formed at an upper portion or lower portion of the washer coil. Otherwise, a ground plane layer is formed with an interlayer insulation film sandwiched, in a position, except for a detection coil, particularly, of an upper layer or lower layer, of a washer coil being magnetically coupled to a feedback-modulation coil to which a signal is sent from an external control system. As a result, it is possible to prevent an external magnetic field from being coupled to other regions than the detection coil and hence accurately measure a magnetic field linked to the detection coil. In particular, the invention is effective for a reduced detection area of a detection coil thus suited for measurement on high spatial resolution.
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