THERMALLY ACTIVATED FLUX DISSIPATION IN C-AXIS-ORIENTED YBA2CU3O7/PRBA2CU3O7 MULTILAYERS

We have systematically studied the resistive transition of multilayers of YBa2Cu3O7/PrBa2Cu3O7 (YBCO/PBCO) under different perpendicular magnetic fields. It was found that the resistive transition is dominated by the flux-thermal-activation process; the broadening of the resistive transition was observed with the same order as that in single-layer thin films and the resistivity obeys the relation rho=rho0 exp(- U/kT). The activation energy depends logarithmically on the applied magnetic fields and decreased linearly with temperature. This phenomenon may be attributed to the creation of edge-dislocation pairs in the two-dimensional pancake vortices situated in the individual YBCO layer. The possible pinning mechanisms in the multilayers are discussed.