FIELD-INDUCED FLUX-PINNING IN ND1-XCU3O7-DELTA SINGLE-CRYSTAL(XBA2)

The flux pinning behavior of a Nd1-xBa2-xCu3O7-delta (Nd123) single cr ystal, which exhibited a peak effect, has been studied by monitoring t he time decay of the magnetic moment. The apparent pinning energy (U-0 ) was deduced from flux creep data on the basis of the Anderson-Kim m odel. The magnetic field dependence of U-0 showed maxima at peak fiel ds which depended on the temperatures, in a similar manner to those of critical current densities. In addition, the temperature dependence o f U-0 showed several features. To explain the increase in U-0* with t he field as well as its temperature and field dependence, we made a nu merical calculation by introducing an additional pinning energy which increased with increasing field. The results are in good agreement wit h the experimental data, especially at temperatures above 60 K, where the contribution of field induced pinning centers is believed to be do minant. (C) 1997 Elsevier Science B.V.