In-plane epitaxial alignment of YBa2Cu3O7−x films grown on silver crystals and buffer layers

Superconducting YBa2Cu3O7−x (YBCO) films were grown by laser ablation on Ag(001), Ag(110), and Ag(111) single-crystal surfaces. X-ray diffraction measurements showed that, in all cases, the films were aligned with specific in-plane epitaxial orientation with respect to the crystallographic axes of the substrate. The observed orientations were consistent with predictions of near-coincident site lattice models of the YBCO-Ag interface. This technique for achieving three-dimensional film alignment was extended to include a Ag epitaxial buffer layer on mica in place of a bulk Ag crystal. In-plane epitaxial alignment on metal substrates and buffer layers has important consequences in practical applications for inhibiting weak-link behavior caused by high-angle grain boundaries.