High critical currents and flux creep effects in e gun deposited epitaxially 00L oriented superconducting YBa2Cu3O7 d films
Thin films of YBa2Cu3O7 d have been made by codeposition of Cu, Y and BaF2 in a UHV system. Annealing in humid oxygen at 835 degC produces high quality single phase preferentially c oriented films. In 1000 A thin films the transport current density is larger than 106 A/cm2 at 86 K. Even 500 A films prove to be superconducting above 77 K. Extrapolation to zero field of the magnetization data obtained from torque experiments are consistent with the current transport data. This indicates that the sample is homogeneous and the critical state model can be applied. Both magnetic relaxation measurements and flux creep resistivity in a magnetic field indicate the importance of thermally activated processes.