Abstract We investigated the influence of surface damage on the critical current density (Jc) of MgB2 thin films via 140-keV Co-ion irradiation. The Jc(H) of the surface-damaged MgB2 films was remarkably improved in comparison with that of pristine films. The strong enhancement of Jc(H) caused by a surface damage in MgB2 films can be ascribed to additional point defects along with an atomic lattice displacement introduced through low-energy Co-ion irradiation, which is consistent with the change in the pinning mechanism, from weak collective pinning to strong plastic pinning. The irreversible magnetic field (Hirr) at 5 K for surface-damaged MgB2 films with a thickness of 850 and 1,300 nm was increased by a factor of approximately 2 compared with that of a pristine film. These results show that the surface damage produced by low energy ion irradiation can serve as an effective pinning source to improve Jc(H) in a MgB2 superconductor.

中文翻译：

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表面损伤对MgB2薄膜临界电流密度的影响

摘要 我们研究了表面损伤对 MgB2 薄膜通过 140-keV Co 离子辐照的临界电流密度 (Jc) 的影响。与原始薄膜相比，表面受损的 MgB2 薄膜的 Jc(H) 显着提高。MgB2 薄膜表面损伤引起的 Jc(H) 的强烈增强可归因于额外的点缺陷以及通过低能 Co-离子辐照引入的原子晶格位移，这与钉扎机制的变化一致，从弱集体钉扎到强塑性钉扎。与原始膜相比，厚度为 850 和 1,300 nm 的表面受损 MgB2 膜的不可逆磁场 (Hirr) 在 5 K 下增加了大约 2 倍。