PREPARATION AND ROOM-TEMPERATURE ION IRRADIATION OF SPUTTERED YBACUO - FILMS

YBaCuO-films (typical thickness 350 nm) were prepared by hollow-cathode dc-magnetron sputtering under optimized conditions onto yttria-stabilized ZrO2 (YSZ) substrates (100-oriented). The as-prepared films were characterized by x-ray texture analysis and found to be epitaxially grown with c-axis orientation ( mosaic spread < 0.3-degrees). In addition, after lateral structuring by lithography and wet-chemical etching, the critical current densities were determined by transport measurements resulting in a maximum critical current density at 77 K of 4.10(6)A/cm 2 without an external magnetic field. By bombarding these bridges at 300 K with 200 keV He+ ions, the superconducting transition temperature T(c), the resistivity rho and the critical current density j(c) could systematically be changed. In all cases, j(c) reacted most sensitively to ion bombardment resulting in a strong decrease, which is in detail dependent on the film quality prior to irradiation.