Mesoscopic magnetoquenched superconducting valve

A superconducting switch has been developed using the magnetic fringe field of a ferromagnetic film to control the critical current in an underlying superconducting Sn film. The magnetization of the ferromagnet is rotated in the plane of the film to vary the magnitude of the fringe field applied locally to the superconductor from negligible to substantial values. A large suppression of the critical current is observed. Applications as an amplifier and a nonvolatile storage cell are possible, and a device based on high T-c materials has promise. (C) 1997 American Institute af Physics.