EPITAXIAL BAXSR1-XTIO3 YBA2CU3O7 BILAYERS FOR TUNABLE MICROWAVE APPLICATIONS/

The feasibility of epitaxial BaxSr1-xTiO3/YBa2Cu3O7 bilayers was studi ed for tunable microwave antennae applications. Ferroelectric BaxSr1 - xTiO3 (BST) was epitaxially coupled to YBa2Cu3O7 (YBCO) thin films vi a the pulsed laser deposition technique. Congruent processing paramete rs were used for the growth of both layers and it was found that the s uperconducting phase of the YBCO could still be maintained with suffic ient post-deposition anneal in oxygen. X-ray diffraction and Rutherfor d backscattering spectroscopy results indicate that a mosaic structure was formed in the BST layer. Electrical measurements demonstrate the viability of Ba0.5Sr0.5TiO3 thin films as tuning media for YBCO microw ave antennae as the relative dielectric constant was measured to be 36 0 at 77 K, and 50% modulations were achieved with applied fields as sm all as 4.5 V. Copyright (C) 1996 Elsevier Science S.A.