Superconductivity in high transition temperature copper oxides
Abstract
The recent discovery of a family of metallic copper oxide compounds with unusually high superconducting transition temperatures presents a fundamental challenge to conventional understanding of superconductivity and a unique opportunity for potential applications. In order to explore the scientific and technological advances a range of measurements was made to characterize the normal and superconducting properties of the La-Sr-Cu-O and Y-Ba-Cu-O families which superconduct at 40K and 90K respectively. Resistivity, magnetoresistance, superconducting critical field, Meissner effect, and magnetic susceptibility measurements were performed in samples with various chemical substitutions of magnetic and non-magnetic ions. The role of oxygen deficiency in the Y-Ba-Cu-O was explored. Magnetic ions were found to have little or no effect on the superconducting properties of both families. Values of the specific heat coefficients were derived from the critical field measurements. When combined with existing measurements of the discontinuity in the heat capacity at the transition temperature, these measurements show that the La-Sr-Cu-O family lies well in the strong coupling regime, whereas the Y-Ba-Cu-O family may lie closer to the weak coupling limit. Oxygen deficiency in the Y-Ba-Cu-O system was found to have a dramatic effect on the superconducting transition temperature.
Degree
Ph.D.
Advisors
Reifenberger, Purdue University.
Subject Area
Condensation
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.