Melt-textured NdBa2Cu3Ox, (Ndl23) exhibits the secondary peak effect on the magnetic field dependence of the critical current density (Jc), which is attributed to the field-induced pinning. The electric field (E)-the current density (J) characteristics will be affected by the field-induced pinning. With the aim of clarifying this effect, we have investigated the E-J characteristics for melt-textured Nd123 with the secondary peak and Yba2Cu3Ox (Y123) with smaller secondary peak through dc magnetization and ac susceptibility. The n value was estimated on the assumption that E follows the power law: E = Ec(J/Jc)n. The n value was about 30 at 77 K for Y123. In the case of Nd123, the peak structure was observed on the magnetic field dependence of the n value, which exceeded 60 at 77 K. This suggests that the n value is increased by the field-induced pinning.
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