Enhanced flux pinning properties of YBa2Cu3Oy by dilute impurity doping for CuO chain

Effects of dilute impurity doping to the CuO chain of Y123 on the flux pinning properties were studied using single crystals and melt-solidified bulks. Cobalt-doped Y123 single crystals and iron-, cobalt- or gallium-doped Y123 melt-solidified bulks exhibited dramatically improved J(c)-H characteristics accompanying huge secondary peaks in J(c)-H curves. In field J(c) of these samples are apparently higher than that of a low level zinc-doped bulk. These results strongly suggest that introduction of local disorders in the CuO chain by dilute impurity doping is a more promising way to improve J(c) of RE123 materials than impurity doping to the CuO2 plane. (c) 2006 American Institute of Physics.