Superconductive Electronic Devices Using Flux Quanta.

Abstract

Abstract : This research involved the study of electronic devices using quantized magnetic flux lines in long Josephson junctions and in superconductive films. The work involved fabrication and electrical measurement, coupled with physical modelling, of device configurations. The Josephson structures studied included the junction vortex flow transistor made with both low and high transition temperature superconductors and a niobium device which proved to be an interesting dual to a semiconductor diode. A laser ablation system was built for deposition of the thin films. Films from this system and from other laboratories were used in a coordinated study of the magnetic field sensitivity of thinned links. The results of this study showed too little sensitivity for practical Abrikosov vortex flow transistors to be realized. A parallel study on granular films yielded similar results. It was concluded that Josephson based devices had much more potential. Subsequent study was conducted on grain boundary Josephson junctions and junctions made by oxygen depletion caused by a narrow electron beam. Long Josephson junctions were made and characterized. Vortex flow transistor structures, using long junctions and junction arrays have been designed. (MM)