Influence of anisotropically splayed columnar defects on the angular dependence of critical current density in YBCO thin films

Sueyoshi, Tetsuro*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito   

Columnar defects (CDs) produced by heavy-ion irradiations in high-Tc superconductors such as YBaCuOy (YBCO) are the most effective pinning centers to immobilize flux lines, leading to the enhancement of critical current density Jc. In addition, slight dispersion (splay) in directions of CDs can further improve the Jc. In this work, YBCO thin films were irradiated using 200 MeV Xe ions at two angles relative to the c-axis in two geometries where the direction of current is perpendicular (mode A) or parallel to the splay plane (mode B), to investigate the influence of the direction of splay plane on the flux pinning properties.