Effects of Y substitution on the temperature and field dependence of magnetic hystereses in YxGd1-xBa2Cu3O7-δ

Effects of Y substitution on the magnetic hystereses are investigated in Y-substituted YxGd1-xBa2Cu3O7-δ ceramics. Magnetizations are first measured at respective constant temperatures, where the hysteresis ΔM is estimated by the magnetization difference between field increase and decrease. When the variations of ΔM for the identical field against temperatures are examined, ΔM is found to obey ΔM=Aexp[-T/T0] with the single T0 for a given field. The characteristic temperature T0 is in the range of 10-30 K, and the field dependence is compared with the function: H-1/n. The field dependence of T0 for the x=0.2 (nominal) sample is larger than that for the pure Gd123 ceramics of x=0, reflecting larger T0 at lower magnetic fields. This is owing to larger ΔM at higher temperatures and lower fields in the Y-substituted system. Improvement of the intergrain coupling by the Y substitution is discussed in comparison with magnetic behaviors in the pure sample