Microwave measurements of high Tc superconductors

The parallel plate resonator has been used for measuring high Tc superconductors. This method is used to measure superconducting c-axis oriented YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// /spl sim/1 cm/sup 2/ thin films. These /spl sim/1 cm/sup 2/ films were grown by two methods: pulsed laser deposition and DC sputtering. Using this method a high resolution surface resistance is calculated directly from the measured unloaded quality factor. The method provides relatively accurate and sensitive measurements of the penetration depth. The change in the penetration depth at the low temperature range reflects the superconducting microscopic state. The parallel-plate resonator method has a resolution of a few /spl Aring/ in the penetration depth measurements.