Microstructure and Temperature Dependence of Microwave Penetration Depth of Ag-YBa_2Cu_3O_7-#delta# Thin Films

摘要

We report the measurements of the magnetic penetration depth #lambda#(T) of Ag-doped YBa_2Cu_3O_7-#delta# (YBCO) thin films in the film thickenss ragne 1500-4000A and temperature range 18-88K. The films are insitu grown by laser ablation on LaAlO_3 <100> single crystal substrates. The penetration depth measurements are performed by microstrip resonator technique. A correlation of #lambda#(T) with the film microstructure observed with Atomic Force Microscopy has shown that #lambda#(T) depends critically on the film microstructure. Temperaure dependence of #lambda#(T) has alos been studied for best quality films. The experimental results are discussed in terms of BCS theory (s-wave pariing) and d-wave Pairing with and without impurity scatteirng. The results are found to be best fitted to the d-wave model in dirty limit with impurity scattering. Near Tc, we have alos compare the (3D) XY critical regime and the Ginzburg-Landau (GL) behaviour.