CHARACTERIZATION OF TETRAGONAL 1-2-3-(CAXLA1-X)(BA1.75-XLA0.25-FILMS PREPARED BY LASER-ABLATION DEPOSITION(X)CU3OY THIN)

Tetragonal c-axis oriented films of 1:2:3 (CaxLa1-x)(Ba1.75-xLa0.25+x) Cu3Oy (CLBCO) were prepared from a target with x = 0.45 and T-c onset approximate to 81.5 K. The cation composition was controlled by changi ng the distance D-ts between the target and the substrate. T-c onset a nd T-c(R = 0) of the films were 78 K and 75 K on (110) LaGaO3 (LGO) su bstrates, 72 K and 69 K on (100) MgO, and 72 K and 65 K on (100) SrTiO 3 (STO), respectively. The width of the rocking curves of the films on LGO, MgO and STO were 1.8 degrees, 1.5 degrees, and 0.3 degrees, resp ectively, indicating a correlation between a high T-c(0) and increased mosaicity. This could be due to a shorter diffusion path of oxygen an d improved uptake at high degree of mosaicity. The large rho(ab)(300 K ) (approximate to 550 mu Omega cm) and the small rho(ab)(300 K)/rho(ab )(100 K) ratio (less than or equal to 1.8) in our films compared to YB CO, suggests that the CuO2 planes are the main conduction element in C LBCO, consistent with total chain disorder in the basal plane of CLBCO . The relatively low J(c)(40 K) approximate to 10(6)A/cm(2) in our fil ms, may result from the absence of twins (pinning centers).