UBC Theses and Dissertations
Studies of the frequency dependence of the microwave surface resistance of high Tc superconducting films using a new superconducting split ring resonator Gowe, Bruce T.
A new superconducting split-ring resonator has been developed for use in perturbation measurements of the microwave surface resistance of thin superconducting films. The experimental setup allowed for the sample temperature to be ramped from 10 - 120 K during the measurement. The split ring arrangement was such that it could be adjusted from run to run to operate at a variety of frequencies thus making the apparatus well suited to exploring the frequency dependence of the film's losses. Results from measurements on Tl2Ba2CaCu20y films with this resonator at 910 MHz, 1.4 GHz and 2.4 GHz in conjunction with results from an earlier split-ring resonator at 3.7 GHz  suggest that the losses are not consistent with an UJ2 relationship below 2.4 GHz. Operating at 910 MHz, surface resistances as low as 5/J.Q were easily resolved with perturbations from an unloaded quality factor of 2xl06 . The 2.4 GHz configuration had a resolution of ILIQ in surface resistance.