Investigation of microwave current effect on parameters of YBCO thin filmsin microstrip resonator structure

The effect of microwave (MW) current on the parameters of YBCO thin films d eposited on LaAlO3 substrates was investigated at 77 K and 4.23 GHz using t he microstrip resonator technique. Approximate expressions for the hysteret ic loss contribution to the HTS film surface resistance were drawn and used to interpret the MW current dependence of the surface resistance. Informat ion about the critical current density, the current dependent part of the s urface resistance and the penetration depth of the vortex Lines were obtain ed by this approach for YBCO films of different quality. (C) 1999 Published by Elsevier Science B.V. All rights reserved.