Effects of oxygen ion implantation on single-crystalline MgB_2 thin films

摘要

We studied the effects of oxygen (O) ion irradiation on superconducting properties of single-crystalline MgB2 thin films with various thicknesses (130, 410, 850, and 1300 nm). Low irradiation energy was used to implant ions into the films. The correlation thickness of the top-implanted layer and the thickness of the bottom-clean layer could be adjusted by controlling irradiating energy. An interesting exponential dependence of T-c on the thickness ratio of these layers was found possibly due to the conventional proximity effect. The MgO, which is known as an effective pinning source for MgB2, was induced in implanted films. Thus, despite the use of low irradiation energy, the field performance critical current density, J(c)(H), was significantly improved in most cases of irradiated films. The pinning force density (F-p) showed a crossover from surface pinning to a normal point pinning mechanism. These results indicate that the superconducting and the pinning mechanism in single-crystalline MgB2 could be well managed by the oxygen ion implantation. Published under license by AIP Publishing.