Sr2AlTaO6/ YBa2Cu3O7 Heterostructures for Superconducting Device Applications

Using pulsed laser deposition, we have prepared epitaxial heterostructures of a new insulating perovskite Sr2AlTaO6 (SAT) and the high temperature superconductor YBa2Cu3O7 (YBCO) on LaA103 substrates. X-ray rocking curve and Rutherford backscattering channelling measurements on [001] SAT films on [001] LaA103 substrates yield full width at half-maximum of < 0.3° and minimum backscattering yield xmin of 5 %, respectively, indicating good crystallinity. From capacitance measurements on SAT films, the real part of the relative dielectric constant er is found to be ~ 23 - 30, with ~ 6xl07 V/m static breakdown electric field. A 100 nm x 10 |im x 50 |am YBCO film on SAT shows zero-field critical current density of ~ 1.3xl06 A/cm2 at 77 K. Using a dielectric resonator at 24.5 GHz, we have measured the resistive energy dissipation at the surface of a YBCO/SAT/YBCO trilayer, yielding effective surface resistance value of ~ 12 mQ, at 77 K, which is within a factor of four of the value obtained for a single layer YBCO film.