Abstract: A superconducting loop is formed by two Josephson junctions connected to both ends of a washer coil which serves also as a pick-up coil. The washer coil which is a magnetic field detection portion is constituted by two coils, i.e., a coil having a radius r.sub.1 and a number of turns n.sub.1 and a coil having a radius r.sub.2 and a number of turns n.sub.2 which are in the form of concentric circular loops. The two coils are coupled in opposite directions and are designed so that effective areas n.sub.1 .pi.r.sub.1.sup.2 and n.sub.2 .pi.r.sub.2.sup.2 are equal to each other. Since a magnetic field is directly detected by the washer coil, sensitivity to a magnetic field is enhanced. This makes it possible to obtain sufficient sensitivity to a magnetic field even if the area of the magnetic field detection portion is reduced to improve spatial resolution.

Abstract: A method of manufacturing a DC superconducting quantum interference device comprises forming an insulating film over a portion of a resistance film. A lower electrode superconducting film is formed over the resistance film and the insulating film. A barrier layer is formed on a portion of the lower electrode superconducting film. An upper electrode is formed sandwiching the barrier layer between the lower electrode superconducting film and the upper electrode, so as to form a Josephson junction. To reduce the number of manufacturing steps, the lower electrode superconducting film is photolithographically patterned and/or etched to simultaneously form an input coil, a feedback coil and the Josephson junction. In another embodiment, after forming the upper electrode, an insulating film is formed over at least a portion of the lower electrode superconducting film. A superconducting film is formed over the insulating film in contact with the upper electrode.