Cascade defects as flux pinning centers in Bi2Sr2CaCu2Ox single crystal generated by ion irradiation

Abstract

Cascade defects generated by ion irradiation in BI2212 single crystal were investigated by transmission electron microscopy (TEM). The irradiation was performed by 18 MeV Fe8+ ions at Ixl012ions/ cm2. The size and distribution of cascade defects were quantitatively measured by using an image analysis method. TRIM cord was applied to theoretical calculation compared with the results obtained from quantitative measurement results. The calculation results were consistent with experimental. Meanwhile, the differences of magnetization before and after irradiation were detected by SQUID measurements. The size and distribution of the cascade defects were found to be much influential for enhancement of critical current density. The relationship between irradiation condition and cascade defect can be used to form a model sample for controlling flux pinning centers with optimum size. In addition, the critical current density and cascade defects induced by 18, 14, and 10 MeV Fe ion irradiation along c-axis were also studied. The critical current density of this sample was compared with that of 18 MeV Fe8+ ion irradiation sample in same fluence.