Flux pinning characteristics and material power law of melt-textured YBa₂Cu₃O7-delta

Low-electric-field E - J curves of YBa 2 Cu 3 O 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 U 0 ( 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 U 0 with temperature in high temperature superconductors (HTSCs).