Masters Theses

Date of Award

8-2007

Degree Type

Thesis

Degree Name

Master of Science

Major

Physics

Major Professor

James. R. Thompson

Committee Members

Pengcheng Dai, Tolga Aytug

Abstract

High-temperature superconductivity has been a focus of much study over the past 20 years, particularly within the cuprate class of superconductors. The effectiveness of these cuprate superconductors is limited by factors including the formation of vortices within the superconductor, orientation within external magnetic fields, the strength of these magnetic fields, temperature, and whether any doping agents have been used. Any of these factors individually can affect the transport critical current levels. In this research, YBaCuO and NdBaCuO-based coated conductors were studied in a liquid-nitrogen-cooled environment at either 77 K or 65 K. Field levels were varied between 0 T and 8 T while orientation was held constant, as well as orientation varying through 140 degrees of rotation while the field was held constant. From the data, n-values (in the voltage-current power-law relation V / In) and ff values (a power-law relation Jc / Hff) were calculated, and plots of angular and field dependencies were made. The results showed parallels between doping and improved pinning ability of vortices in addition to an unsuspected weak variation of n-values in relation to orientation within constant magnetic fields.

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