Hysteretic behavior of the transport critical current density in a bent Bi-Pb-Sr-Ca-Cu-O silver sheathed tape

Abstract

The hysteretic behavior of transport critical current density of a flexible Bi-based tape with bending strain has been investigated. After zero field cooling (ZFC), the experimental data obtained at 77 K under field cycling in the range of applied field from 0 to 1000 G to 0, indicate that the hysteretic ΔJc(H,ε), which is defined as the difference between the transport critical current Jc(H,ε) in an increasing field and decreasing field H, do not vary when bending strain ε is smaller than a critical bending strain εb, and then decreased gradually with increasing bending strain, but the normalized ΔJc(H,ε)/Jc(H,ε) values are unaffected by the bending strain up to 0.8%. Furthermore, the family of curves of Jc(H,ε)/Jc(0,ε) are independent of bending strain and can be described by an empirical expression, which is analogous to formulae exploited in the generalized critical state model.