OBSERVATION OF GIANT FLUX-FLOW IN SUPERCONDUCTING YBA2CU3O7-DELTA FILMS

Measurements of field-induced changes the a-b plane surface resistance of high quality (> 10(6) A/cm(2) at 77K and H=0) YBa2Cu3O7-delta film s at 12.92 GHz reveal enormous flux-flow resistivity at temperatures s everal degrees below the superconducting onset temperature. Flux-flow resistivity is identified by its dependence on the Lorentz force. The results suggest that large scale effective pinning is not responsible for the high critical current density observed in these films; a reduc tion in structural defects and improved oxygen vacancy ordering may be of greater importance.