MULTILAYER PINNING IN A-AXIS-ORIENTED EUBA2CU3O7 PRBA2CU3O7 SUPERCONDUCTING SUPERLATTICES/

a-axis EuBa2Cu3O7/PrBa2Cu3O7 superlattices and a-axis films have been grown by de sputtering to study the interplay between the natural mate rial anisotropy (Cu-O planes) and the artificial layered structure (Pr Ba2Cu3O7 layers). These a-axis-oriented superlattices are unique becau se, in comparison with c-axis superlattices, they allow one to separat e both effects: in c-axis multilayers Cu-O planes and the artificial l ayers are parallel whereas in a-axis multilayers the intrinsic and the artificial layers are perpendicular to each other. When B is parallel to the substrate plane, the superlattices show an enhancement of the pinning force in comparison with the behavior of the films that is con trolled by the EuBa2Cu3O7 layer thickness. If B is perpendicular to th e substrate plane, the flux motion presents a log B dependence of the activation energy up to at least, 40-unit-cell-thick layers.