Fabrication of SmBa2Cu3O7 films on CeO2 buffered sapphire

SmBa2Cu3O7-delta (SmBCO) thin films and CeO2 buffer layers were deposited on gamma-cut sapphire by pulsed laser deposition (PLD) and characterized with X-ray diffraction (XRD) and atomic force microscope (AFM). The theta-2 theta XRD scans of the SmBCO/CeO2/sapphire structures revealed that the CeO2 and SmBCO films were grown with c-axis perpendicular to the substrate. In Phi-scan XRD patterns, four (103) peaks of the SmBCO film were observed and the peak positions were shifted by 45 degrees from (202) peaks of the CeO2 films. From the peak shifts we could conclude that the [110] SmBCO crystal axis is parallel to the [100] CeO2 crystal axis. Moreover, pole figure also confirmed that SmBCO films were grown on the substrates epitaxially along in-plane direction. The SmBCO films show very flat surfaces with root mean square (RMS) about 5 nm. In agreement with this crystalline perfection, SmBCO thin films present excellent superconducting properties: T-c0 > 90 K, transition width 0.4 K, and J(c)(77K) > 2MA/cm(2).