Combined effect of flux pinning by three-directional columnar defects in a field-angular region of high- superconductors

Sueyoshi, Tetsuro*; Enokihata, Ryusei*; Hidaka, Yuka*; Irie, Masahiro*; Fujiyoshi, Takanori*; Okuno, Yasuki*; Ishikawa, Norito   

We investigated the combined effect of flux pinning by three-directional columnar defects (CDs) in a wide field-angular range of YBaCuOy thin films, where CDs parallel to the -axis and CDs crossing at (=45, 60 and 80) relative to the c-axis were installed by 200 MeV Xe-ion irradiations. The three-directional CDs with 60 form a field angular curve of critical current density Jc with a broad peak centered at magnetic field (B) parallel to the -axis, whereas the Jc shows no peaks around the crossing angles of . When the crossing angle is expanded to =80, a drastic change in the field- angular behavior of Jc is induced: there is not a large enhancement of around B//c. We also demonstrated that the combined configuration consisting of CDs at = 0, 45, 60 and 80 provides a uniform enhancement of over a wide angular-region.