Effect of silver doping on the transport properties of epitaxial YBa2Cu3O7−x thin films

Epitaxial YBa2Cu3O7 (YBCO) thin films doped with 5–20 wt % Ag have been grown “in situ” at high oxygen pressure by a dc sputtering technique on (001) SrTiO3 substrates. Critical current densities, Jc, were measured in 5 wt % Ag-doped YBCO films in magnetic fields up to 6 T, and were found to be greater than the values obtained for undoped samples. Current-voltage (I–V) characteristics were used to investigate the vortex phase transition, in magnetic field of 6 T applied parallel to the c-axis. The ϱ-j curves scale according to the 3D vortex-glass (VG) model with values of the critical exponents similar to those found for undoped YBCO samples (ν=1.4 and z=4.87).