Improvement in crystal orientation and in-plane alignment of La-doped YBCO thin film on BaZrO_3-buffered MgO substrate

摘要

Y_(0.9)Ba_(1.9)La_(0.2)Cu_3O_y (La-YBCO) thin films were prepared by an off-axis magnetron sputtering method on MgO substrates with and without a BaZrO_3 buffer layer. Insertion of BaZrO_3 buffer layer was effective for obtaining La-YBCO films with pure c-axis orientation and in-plane alignment at low temperatures below 600 deg C. We prepared La-YBCO thin films on BaZrO_3-buffered MgO substrates using a temperature-gradient method, in which a template La-YBCO layer was first deposited at 600 deg C, and then the temperature was continuously raised to 700 deg C. By this method, La-YBCO thin films with improved crystallinity were successfully prepared. It was also proved that the insertion of the BaZrO_3 buffer layer enables us to prepare high-quality La-YBCO films with high reproducibility.