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 LaAlO3 substrates. X-ray rocking curve and Rutherford backscattering channelling measurements on [001] SAT films on [001] LaAlO3 substrates yield full width at half-maximum of < 0.3 degrees and minimum backscattering yield chi(min) of 5 %, respectively, indicating good crystallinity. From capacitance measurements on SAT films, the real part of the relative dielectric constant epsilon(r) is found to be similar to 23 - 30, with similar to 6x10(7) V/m static breakdown electric field. A 100 nm x 10 mu m x 50 mu m YBCO film on SAT shows zero-field critical current density of similar to 1.3x10(6) A/cm(2) 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 m Omega at 77 K, which is within a factor of four of the value obtained for a single layer YBCO film.