Sr₂AlTaO₆ films for multilayer high-temperature superconducting device applications

Thin films of Sr₂AlTaO₆ (SAT) and multilayers of YBa₂Cu₃O₇ (YBCO)/SAT have been grown by pulsed laser deposition on [001] LaAlO₃ substrates. X-ray diffraction shows that SAT grows on [001] LaAlO₃ with the c-axis oriented normal to the substrate plane. X-ray rocking curve and Rutherford backscattering channeling measurements on SAT films yield full width at half maximum of <0.3°and minimum backscattering yield χ_min of 5%-7%, respectively, indicating good crystallinity. The real part of the dielectric constant ε_r is found to be ∼23-30, with ∼6×10⁷ V/m static breakdown electric field. Both the dielectric constant and the static breakdown field show negligible temperature dependence between 10 and 300 K. A 100 nm×10 μm×50 μm YBCO film on SAT shows zero-field critical current density of ∼1.3×10⁶ A/cm² at 77 K, with a superconducting transition temperature T_c0 of ∼89.2 K.