MICROWAVE PENETRATION DEPTH MEASUREMENTS OF AG-YBA2CU3O7-DELTA THIN-FILMS

The penetration depth lambda of 5 wt.% Ag-doped YBa2Cu3O7-delta (YBCO) thin films has been measured using microstrip resonator technique. Th e films are grown in situ by laser ablation on [1 0 0] LaAlO3 substrat es. We found a minimum value of surface resistance, R-s of 215 mu Omeg a at 77 K and 10 GHz for a film thickness of about 3000 Angstrom. Temp erature dependence-of magnetic penetration depth has also been studied for best quality films in the temperature range of 18-88 K. The exper imental results are discussed in terms of BCS theory (s-wave pairing) and d-wave pairing with and without impurity scattering. The correspon ding value of lambda (0) has been found to be 1400 Angstrom for Ag dop ed YBCO film. (C) 1998 Published by Elsevier Science Ltd.