Laser-ablation studies of highly-oriented thin films of the electon-doped infinite-layer copper-oxide compounds Sr1 - xCuO2 are reported. We observe significant variations in film properties with substrate or buffer layer material. X-ray diffraction, atomic force microscopy (AFM), Rutherford back-scattering (RBS), and electrical resistivity were used to characterize the films. Films were deposited on strontium titanate (001) or on buffer layers of T′-phase copper oxides (Ln2CuO4 with Ln = Pr, Nd, Sm), Sr3FeNb2O9, and La1.8Y0.2CuO4 on SrTiO3 (001). The in-plane lattice constants of such buffer layers (a = 0.390-0.400 nm) should provide the bond tension required for electron doping. Extremely flat, epitaxial buffer layers with X-ray rocking curves as narrow as 0.08° were obtained from stoichiometric targets of Ln2CuO4; the other buffer layers yielded poor epitaxy. A linear dependence of infinite-layer c-axis plane spacing on substrate or buffer-layer in-plane a-axis lattice constant is observed.@en

We report the results of laser ablation studies of T′-phase copper-oxide compounds. Variations in film morphology as a function of deposition parameters are discussed. Highly-oriented films were obtained, and a true step-flow growth mode accompanied by a coherent tilt boundary was observed.@en

In a recent paper [1], it has been shown from transport measurements that artificial reversible pinning can be created by the application of a magnetic tape on the surface of a thin superconducting film. We study the influence of a periodic array of magnetic stripes, generated from a signal pre-recorded on a magnetic tape, on the pinning of vortices. With our high resolution magneto-optical technique [2], we visualize in two dimensions the penetration of the flux in a thin YBa2Cu3O7-δ film partially covered by such a magnetic tape. In particular, we investigate the evolution of flux entry in the superconducting strip under and next to the magnetic tape. We present results obtained for various temperatures and various applied fields.@en