Flux pinning properties in GdBCO coated conductors containing columnar defects with splay plane parallel to current direction

Abstract

In order to reveal the influence of crossing angle of one-dimensional pinning centers on angular dependence of critical current density Jc, heavy-ion irradiation was performed to introduce columnar defects (CDs) crossing at ±θi relative to the c-axis into GdBCO coated conductors, where the splay plane consisting of the two directions of CDs is parallel to the current flow direction. For the sample containing CDs with θi=±15°, a single and sharp peak was observed around B || c in the angular dependence of Jc. When the crossing angle was extended to ±45°, the single Jc-peak became broader, which was a gently-sloping mountain-like shape centered at B || c. For θi=±75°, on the other hand, a quite different behavior of Jc from the other irradiated samples was observed, which was analogous to the angular dependence of Jc typical of three dimensional pinning centers.