Influence of magnetic field on the flux motion in superconducting YBCO/PYBCO superlattice

Angular dependent critical current densities J/sub c/(H,/spl theta/) for the YBa/sub 2/Cu/sub 3/O/sub 7-y//Pr/sub 0.5/Y/sub 0.5/Ba/sub 2/Cu/sub 3/O/sub 7-y/ (120 /spl Aring//24 /spl Aring/)/spl times/8 superlattice under various magnetic fields were measured to investigate the influence of the applied magnetic fields on the dimensionality of the flux pinning and flux dynamics. J/sub c/(H,/spl theta/) was obtained by applying current through x- or y-direction and analyzed by Kes model. It is found that the dissipation of the flux line system in the mixed state is mainly due to the pancake motion along ab-plane as H<1 T, while the flux lines begin to move along c-axis when the magnetic field reached 1 T. The causes will be discussed.