MICROWAVE COMPATIBLE YBA2CU3O7-X FILMS ON FERRIMAGNETIC GARNET SUBSTRATES

High quality epitaxial YBa2Cu3O7-x (YBCO) thin films have been deposit ed onto ferrimagnetic yttrium iron garnet (100) substrates using a dou ble 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 exh ibited J(c)'s of 2.7 x 10(6) A/cm(2) in zero field and 1.1 x 10(6) A/c m(2) in 2000 G at 77 K. Dielectric resonator measurements indicated un loaded Q values of 29 000 at 77 K and 24 GHz for unpatterned films. Th ese values correspond to a surface resistance (R(S)) of 500 mu Omega a t 77 K, 10 GHz, which is the lowest obtained to date for a YBCO film o n 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 in tegration on a single ferrimagnetic wafer. (C) 1995 American Institute of Physics.