Enhanced flux pinning properties of RE123 crystals by dilute impurity doping for Cu–O chain

Abstract

In order to improve the critical current properties of Y123 melt-solidified bulks, low level doping of impurities, such as Co, Fe and Ga, to the Cu site in Cu–O chain was attempted. All these doped samples showed high T c above 90 K. Largely enhanced secondary peaks were observed in their magnetization hysteresis loops at 77 K and J c reached approximately 50 kA cm −2 under 10–20 kOe, while undoped sample exhibited poor J c performance without showing the peak effect. This result suggests that introduction of local disorders in the Cu–O chain by dilute impurity doping is more excellent way to improve critical current properties of the RE123 system than direct impurity substitution for Cu in the Cu–O 2 plane.