Angular behaviors of critical current density J _c and n -values at 77 K, 1 T were investigated in YBCO films with columnar defects (CDs) tilted at small angles to the ab -plane before and after the additional introduction of CDs at different angles, where CDs were installed by heavy-ion irradiations. The enhanced J _c at B || ab by the initial irradiation at θ _i = ±85° relative to the c -axis was reduced by the additional irradiation at θ _i = ±75°, whereas the J _c was increased at the intermediate angle between the two irradiation angles. The addition of CDs at θ _i = 0° also lowered the J _c around B || ab , which were enhanced by the initial irradiation angles of θ _i = ±80°. The n -values, by contrast, were hardly lowered in any direction of magnetic field by the second irradiation: the n -value seems to be determined by a simple sum of the pinning interactions of CDs tilted at different angles. These results suggest that the flux pinning is improved in each direction of the tilted CDs, without impeding the flux pinning in the other CD direction each other. The additional introduction of CDs, however, induces both the reduction of the superconducting percolation path and the irradiation damage to the ab -correlated PCs, resulting in the reduction of J _c .

中文翻译：

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YBCO薄膜中不同角度倾斜的柱状缺陷对通量钉扎的总和

临界电流密度的角行为 Ĵ _c和ñ 在YBCO膜中研究了在77 K，1 T处的值-柱状缺陷（CDs）相对于膜倾斜小角度 b 在以不同角度额外引入CD之前和之后的平面，其中CD是通过重离子辐照安装的。增强型Ĵ _c在乙 || b 通过最初的辐照 θ _i =相对于±85°C 轴被额外的照射减少了 θ _i =±75°，而Ĵ _c在两个照射角之间的中间角处增加。CD的添加位置θ _i = 0°也降低了Ĵ _c左右乙 || b ，这是通过初始的照射角度增强的 θ _i =±80°。这ñ 相比之下，第二次辐射几乎不会在任何磁场方向上降低-值： ñ -值似乎是由以不同角度倾斜的CD的钉扎相互作用的简单总和确定的。这些结果表明，在倾斜的CD的每个方向上的磁通钉扎都得到了改善，而不会互相阻碍在另一个CD方向上的磁通钉扎。然而，CD的额外引入既会导致超导渗流路径的减少，又会导致辐照损伤。b 相关的PC，从而减少了 Ĵ _c 。