Date of Award
Doctor of Philosophy
Physics and Astronomy
A new type of magnetic shielding device has been constructed for use in superconducting microelectronic applications where low ambient magnetic field is desirable. The shield was a specially designed superconducting thin film in the shape of a long cylindri- cal tube with a low pinning material in the central region and high flux pinning regions at the end. It was shown that magnetic flux perpendicular to the axis of a cylinder could be swept out of the interior of the shield by moving vortex-antivortex pairs to one side of the shield where they annihilate. The flux sweeping properties of the shield were found to work well in a small temperature window close to the transition temperature where the critical current for depinning vortices was less than the critical current for the forma- tion of hot spots. Once the vortices are swept out, the shield can be cooled to enhance the Meissner shielding effects against other stray fields. In the course of designing and testing the shield, a systematic;study of flux pinning was made for the low magnetic field regime between 1 mOe and 30 Oe; *DOE Report IS-T-1276. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Ming Ming Fang
Fang, Ming Ming, "Annihilation of vortex-antivortex pairs in a superconducting shield " (1986). Retrospective Theses and Dissertations. 8244.