Enhanced flux pinning properties of Y Ba 2 Cu 3 O y 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 Cu O 2 plane.