HIGH-T-c SUPERCONDUCTING EuBa2Cu3Oy THIN FILMS ON MgO AND YAlO3 FOR COPLANAR DEVICES

We have studied the microwave properties of high-T-c superconducting EuBa2Cu3Oy (EBCO) films on MgO and YAlO3 substrates with low dielectric constants (epsilon=10 and 16, respectively), and a low loss tangent (tan delta<10(-5)). Measurements of surface resistance R-s at 50 GHz in a cavity show that EBCO films exhibit low R-s values (77 K) of 2-10 m Omega. A microstructural study using transmission electron microscopy (TEM) showed that crystal defects related to the in-plane misorientation are observed for films with higher Rs values. The R-s values of the patterned films were measured in a coplanar transmission line resonator. Typical value of patterned films was 28 mu Omega, at 4 GHz and 28 K.