DISSIPATION MECHANISMS IN EUBA2CU3O7 SRTIO3 AND EUBA2CU3O7/PRBA2CU3O7MULTILAYERS/

Superconducting multilayers of c-axis and a-axis oriented EuBa2Cu3O7/P rBa2Cu3O7 and c-axis oriented EuBa2Cu3O7/SrTiO3 have been grown by dc and rf sputtering on (100) SrTiO3 substrates. The critical current den sities and the tails of the resistivity transitions (rho, B) have been used to study the dissipation mechanisms. The activation energy (U) f ollows a log B law in all the systems and textures. A crossover from U = U-0 B-alpha to U = U-0 log B occurs depending on the superconductin g layer thickness. The type of multilayer and texture governs the valu es of the activation energies U-0. The former result seems to be relat ed with the competition between the thickness of the superconducting l ayer and the vortex correlation length, and the latter one (U-0 values ) with the coupling between the superconducting layers.