Preparation of highly crystalline a-axis-oriented YBa2Cu3O7-delta superconducting films by a self-template technique

We have prepared high-quality a-axis-oriented superconducting YBa2Cu3O7-δ (YBCO) films using a self-template method on (100) SrTiO3 (STO) substrates by dc sputtering. X-ray diffraction and transmission electron microscopy analysis showed that the films were grown epitaxially on the STO substrates with the a-axis perpendicular to the surface. The full-width at half-maximum value of 0.081 was measured through the rocking curve of the (200) diffraction peak. The effect of the deposition temperature and the thickness of the template layer and the upper layer on the quality of the films was investigated. We found evidence suggesting that structural strain was present at the interface between the template layer and the upper layer. For the film deposited under optimal conditions, the zero-resistance Tc was 85 K and the transition width was less than 2 K. The anisotropy of normal state resistance and critical current density was also studied. (author)