Intrinsic and extrinsic surface impedance of HTS: T- and H-dependencies

Abstract

The application of HTS is obstructed by high surface impedances and their increases Z(T,f,H/sub rf/) with rf field. To separate intrinsic from extrinsic and rf mode from HTS material properties well characterized films are required. Using TBCCO films and corrosion protected YBCO films well defined material and physical parameter dependencies have been found which for the first time allowed a unique separation of intrinsic surface resistances R/sub int/(T,f,H/sub rf/) from extrinsic residual losses R/sub res/(T,f,H/sub rf/) and shed light onto /spl delta/Z/spl prop/H/sub rf//sup 2/ increases observed in TE/sub 011/ modes. The latter confirms that rf results of TE/sub 01n/-mode end-plate replacements are sensitive tools to study HTS thin film material properties before structuring. Aside from /spl delta/R/sub s/(H/sub rf/)/spl prop/H/sub rf//sup n//spl prop//spl delta/X/sub s/(H/sub rf/), rf measurements in the frequency and time domain yield the ratio r=/spl delta//sub s///spl delta//sub s/ which shows distinct T and f dependencies for various mechanisms and rf modes. r(T,f)/spl ap/1 indicates hysteresis losses of Josephson fluxons governed by the weakest links at the edges of the films, being weighted differently in TE/sub 01n/ and strip-line modes.