STRUCTURAL CHARACTERIZATION AND MICROWAVE LOSS OF ND1.85CE0.15CUO4-Y SUPERCONDUCTING THIN-FILMS ON YTTRIA-STABILIZED ZIRCONIA BUFFERED SAPPHIRE

We have grown superconducting Nd1.85Ce0.15CuO4-y (NCCO) thin films on (1102BAR) sapphire using a yttria-stabilized zirconia (YSZ) buffer lay er, which has been demonstrated to be the best material for the growth of n-type superconducting NCCO thin films. The films are c-axis orien ted, epitaxially grown with a small mosaic spread of 0.2-degrees and a Rutherford backscattering spectroscopy channeling yield of approximat ely 9%. Cross-sectional transmission electron microscopy images reveal a sharp interface between NCCO and YSZ. The microwave surface resista nce of NCCO films on YSZ buffered sapphire at 9.6 GHz is only 80 muOME GA at 4.2 K in zero magnetic field, which is comparable to Y1Ba2Cu3O7- y films at similar reduced temperature, as a consequence of the decrea se of structural imperfection in the film. The temperature dependence of the surface resistance and magnetic penetration depth in these film s further confirms the s-wave BCS nature of NCCO.