Dissipation mechanisms in EuBa/sub 2/Cu/sub 3/O/sub 7//SrTiO/sub 3/ and EuBa/sub 2/Cu/sub 3/O/sub 7//PrBa/sub 2/Cu/sub 3/O/sub 7/ multilayers

Superconducting multilayers of c-axis and a-axis oriented EuBa/sub 2/Cu/sub 3/O/sub 7//PrBa/sub 2/Cu/sub 3/O/sub 7/ and c-axis oriented EuBa/sub 2/Cu/sub 3/O/sub 7//SrTiO/sub 3/ have been grown by dc and rf sputtering on (100) SrTiO/sub 3/ substrates. The critical current densities and the tails of the resistivity transitions (/spl rho/, B) have been used to study the dissipation mechanisms. The activation energy (U) follows a log B law in all the systems and textures. A crossover from U=U/sub 0/ B/sup -/spl alpha// to U=U/sub 0/ log B occurs depending on the superconducting layer thickness, The type of multilayer and texture governs the values of the activation energies U/sub 0/. The former result seems to be related with the competition between the thickness of the superconducting layer and the vortex correlation length, and the latter one (U/sub 0/ values) with the coupling between the superconducting layers.