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

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 ΔJ_c(H,ε), which is defined as the difference between the transport critical current J_c(H,ε) in an increasing field and decreasing field H, do not vary when bending strain ε is smaller than a critical bending strain ε_b, and then decreased gradually with increasing bending strain, but the normalized ΔJ_c(H,ε)/ J_c(H,ε) values are unaffected by the bending strain up to 0.8%. Furthermore, the family of curves of J_c(H,ε)/J _c(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.