The role of multilayering in the significant improvement of structural and superconducting properties in high-Tc films

Abstract

By introducing multilayered structures to YBa2Cu3O7 (YBCO) films, significant improvement of superconducting and structural properties in the obtained multilayers has been obtained. A sandwich-like system with three main YBCO layers of ~300 nm thick and two additional NdBCO layers of about ~50 nm thick in between the YBCO layers exhibits much smoother surface compared to the YBCO films of the same thickness. It has critical current density (Jc) which is not only significantly larger (by a factor > 3) than that obtained in YBCO films with the same thickness (1 μm), but also larger than Jc in mono-layer YBCO films of any smaller thickness. The Jc enhancement is observed in both low field and high field regions, which attributed to a larger filling factor of the multilayer, better grain alignment and additional formation of dislocations at the interfaces between the layers.