MAGNETIC-FIELD DEPENDENCE OF THE CRITICAL CURRENT ANISOTROPY IN NORMAL METAL-YBA2CU3O7-DELTA THIN-FILM BILAYERS

We have measured the transport critical current density (J(c)) in epitaxial quality films of YBa2Cu3O7-delta some of which were covered by thin (10 nm) Ag films. The films, both with and without Ag, had J(c) values greater than 10(6) A/cm2 in liquid nitrogen. The effect of the Ag was to greatly reduce the dependence of J(c) on external magnetic fields in the case where the field was oriented in the plane of the film, that is, perpendicular to the c axis. It is unlikely that the effect is simply due to altered surface pinning, although qualitative agreement with critical state models is observed.