Scaling of the magnetic response and field dependence for the characteristic pinning energy in (Y, Nd)Ba₂Cu₃O_7-δ superconductors

Magnetic hysteresis loops for the superconductor (Y, Nd)Ba₂Cu₃O_7-δ have been measured using a SQUID and a vibrating sample magnetometer. The field dependence of the current density and volume pinning force showed well developed maxima and their temperature-dependent characteristics were used to construct different scaling types. The measurement of magnetic hysteresis loops at different sweep rates enabled the field dependence of the characteristic pinning energy to be determined. In all cases a remarkable consistency with the Perkins et al (1996 Phys. Rev. B 54 12 551) model was found, while the field dependence of the characteristic pinning energy appeared to be inconsistent with the collective pinning theory predication.