2026-09-22T11:05:48Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/31039 2023-07-10 col_2142_5131 col_2142_8859 com_2142_5130 com_2142_8858 com_2142_234

Van Harlingen, Dale J. Mason, Nadya Van Harlingen, Dale J. Ryu, Shinsei Clegg, Robert M. Wistrom, Mark 2012-05-22T00:23:44Z 2012-05-22T00:23:44Z 2012-05 2012-05-22T00:23:44Z 2012-05 This thesis presents the direct observations of magnetic flux vortices in superconducting weakly coupled arrays. Real space images of vortices were obtained for various values of f, the fractional flux per unit cell in the array, and , the strength of the coupling between the islands of the superconducting array. Images and results were obtained for a single vortex in a triangular array, demonstrating the effect of changing , which increased the penetration depth of the magnetic field of the vortex in the sample. The ground state of a triangular array is measured and discussed as a function of f with emphasis for f = 1/4, 1/3 where there are several degenerate ground states corresponding to different vortex patterns. Annealing the arrays at a particular f is also discussed. In particular, for a square array at f = 1/2, the domain walls are the dominant defects, and they move through the sample as the temperature increases resulting in a single domain. The instrument used to perform the experiments, a Scanning SQUID Microscope (SSM), is discussed. The vortices in the superconducting arrays have weak magnetic fields that change over small length scales, requiring certain techniques for measurement. Also presented are the numerical calculations relating the magnetic field output from the SSM to the underlying phases of the array. Item withdrawn by Rebecca Bryant (rabryant@illinois.edu) on 2012-04-19T18:08:07Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Thesis.docx: 111221795 bytes, checksum: dade707d4ff9a9203ddfd80ca52996b4 (MD5) Wistrom_Mark.pdf: 32721623 bytes, checksum: 7a04b4aba6aeddb44cbe07faf59a7538 (MD5) Made available in DSpace on 2012-05-22T00:23:44Z (GMT). No. of bitstreams: 3 Wistrom_Mark.pdf: 34183521 bytes, checksum: 4a88e68755c364e3cb68940c6e72d42d (MD5) Thesis.docx: 111211941 bytes, checksum: cf1f8ed6c806300b988401a43af582f7 (MD5) license.txt: 4062 bytes, checksum: 146c081473bf14f6c7675571a35d8ab8 (MD5) http://hdl.handle.net/2142/31039 en Copyright 2012 Mark Wistrom Scanning SQUID Microscope Superconducting arrays Imaging vortices in superconducting weakly coupled arrays text Physics 1244 Physics 0240 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Physics -UIUC 10KS0240PHD