Flux pinning characteristics and material power law of melt-textured YBa₂Cu₃O_7-

Low-electric-field E-J curves of YBa₂Cu₃O_7- were determined from 0.27 to 1.34 T at various temperatures from 52 to 83 K with the magnetic sweeping method by VSM. Using an empirical material power law E = E_c(J/J_c)ⁿ, we obtained the characteristic pinning potential U₀(T,H) and real critical current density J_c(T,H) by an appropriate definition of E_c. By further investigation of the changing shape of the pinning potential well, we interpreted the peak effect of U₀ with temperature in high temperature superconductors (HTSCs).