E–J characteristics of NdBa2Cu3O7−δ bulk superconductor determined with ac susceptibility

Abstract Electric field ( E )–current ( J ) characteristics of the NdBa 2 Cu 3 O 7− δ (Nd-123) bulk superconductor have been investigated by measuring the third harmonic ac susceptibility. They were compared with E–J characteristics determined with the dc magnetization measurements and magnetic relaxation methods. The n value was estimated on the assumption that E follows the power law: E ∼ J n . We found that the sample, which has the larger secondary peak on the J c – B curve, exhibits the more remarkable peak structure on the magnetic field dependence of the n value.