Fabrication and critical current density analysis of YBa2Cu3O7+(BaSnO3)'/YBa2Cu3O7+(BaSnO3)'' multilayer films

摘要

Multilayers (MLs) comprising of YBa2Cu3O7(YBCO)+BaSnO3(BSO) layers with different BSO content were fabricated, and their critical current density (J(c)) was measured to understand influence of ML structure on vortex pinning. Elongated and segmented nanorods were observed in the MLs, and ab-plane aligned nanoparticles appeared depending on BSO content. When BSO formed only elongated and segmented nanorods in MLs, J(c) exhibited a linear relationship between J(c) in the single layer films. On the other hand, when MLs contained ab-plane aligned nanoparticles in addition to nanorods, J(c) decreased with lower-J(c)-layer fraction more rapidly. These results suggest that J(c) was degraded due to easy vortex flow along the lower-J(c)-layers, and that the acceleration of vortex motion depended on the type of lower-J(c)-layers. Vortex behavior which is not observed in conventional systems such as single layer films and bulk samples is strongly expected in MLs, since fine tuning of pinning center structure is possible.