Impedance properties and microwave magnetic field dependence of surface resistance of YBaCuO

Abstract

The microwave magnetic field IIw dependence of the surface resistance Rs for a YBa₂Cu₃O-δ ceramic and thin film has been studied in 8 mm wave band. It is shown that for the film one of mechanisms consistent with the obtained dependence Rs(Hw) may be microwave-induced flux motion. For the ceramic specimen, the above dependence is in agreement with the model of Sridhar for the nonlinear high-frequency response of a planer superconductor in a current-induced critical state and with Gurevich's theory of the nonlinear dynamics of vortices in high-Jc overdamped Josephson contacts. An approach was applied which allows us to perform measurements without preliminary patterning of the samples.