2006-2

Vortex Pinning State on RE123 Films with c-axis Correlated Disorders

c軸相関ピンを有するRE123膜における磁束ピンニング状態

We study the vortex pinning state for REBa₂Cu₃O_x (RE123,RE: rare-earth) films with various kinds of c-axis correlated pinning. In case of the LTG-Sm123 film, the peak around B//c (θ = 0˚) in the angular dependence of J_c shrinks and almost disappears with increasing a magnetic field but it grows again with further increasing of a magnetic field at various temperatures as shown in the insets of the figure. As a result, the complex vortex pinning state diagram can be described schematically as shown in the figure. In addition, we also found that the vortex pinning state diagram strongly depends on a sort of the c-axis correlated disorders such as columnar shaped precipitates, edge dislocations or columnar defects by fission track and so on.

IMR, Tohoku University: S. Awaji, M. Namba, K. Watanabe
Dep. of Elect. Eng. Sci., Nagoya University: Y. Yoshida
Dep. of Mat. Sci., Kyushu Institute of Technology: K. Matsumoto

Reference: S. Awaji, N. Namba, K Watanabe, M. Miura, Y. Yoshida, Y. Ichino, Y. Takai and K. Matsumoto,
"c-axis correlated pinning behavior near the irreversibility fields",
Appl. Phys. Lett. 90 (2007) 122501.

様々なc軸相関ピンニングを有するREBa₂Cu₃O_x (RE123, RE: rare-earth)膜における，磁束ピンニング状態を調べた．LTG-Sm123膜の場合，挿入図に示すように，c軸相関ピンに由来するJ_cの角度依存性におけるB//c (θ = 0˚)近傍のピークは，磁場の増加と共に一旦消滅した後，不可逆磁場近傍で再度増加することが分かった．この結果から，図のような磁束ピンニング状態図が描かれる．さらに，この磁束ピンニング状態図は，c軸相関ピンの種類によって大きく変化すること見出した．

東北大学金属材料研究所：淡路　智，難波雅史，渡辺和雄
名古屋大学工学部：吉田　隆
九州工業大学工学部：松本　要