Monolithic Integration of Superconducting YBCO and Dielectric SrTiO 3 Films on Polycrystalline Ferrites

Monolithic integration of high-temperature superconducting YBCO and nonlinear dielectric SrTiO 3 films on polycrystalline yttrium-iron-garnet (YIG) substrates represents an advance of great technical significance for dual-tuning (both electrically and magnetically) microwave components. We have solved the problems of crystallographic incompatibility among these materials and the lack of a template for epitaxial growth of SrTiO 3 and YBCO films on polycrystalline substrate. Using a template of biaxially oriented MgO, deposited by an ion-beam-assisted-deposition technique, we have produced device quality SrTiO 3 and YBCO films on polycrystalline YIG substrates. Both SrTiO 3 and YBCO films were c-axis oriented with an in-plane mosaic spread of 7° full width at half-maximum (FWHM) for SrTiO 3 and less than 7° FWHM for YBCO. The YBCO films had transition temperatures above 87 K.