MICROWAVE COMPATIBLE YBA2CU3O7-X FILMS ON FERRIMAGNETIC GARNET SUBSTRATES

High quality epitaxial YBa2Cu3O7-x (YBCO) thin films have been deposited onto ferrimagnetic yttrium iron garnet (100) substrates using a double buffer layer lattice engineering scheme. The YBCO films are c-axis oriented and show superconductive transition temperatures of 88-89 K with transition widths less than or equal to 0.5 K. The films also exhibited J(c)'s of 2.7 x 10(6) A/cm(2) in zero field and 1.1 x 10(6) A/cm(2) in 2000 G at 77 K. Dielectric resonator measurements indicated unloaded Q values of 29 000 at 77 K and 24 GHz for unpatterned films. These values correspond to a surface resistance (R(S)) of 500 mu Omega at 77 K, 10 GHz, which is the lowest obtained to date for a YBCO film on a ferrimagnetic substrate. Such films could be used for fabricating miniature-high-temperature superconducting microwave elements such as nonreciprocal and passive microwave devices, making possible, their integration on a single ferrimagnetic wafer. (C) 1995 American Institute of Physics.