Abstract
Anomalous magnetization on several single crystals of Nd1.85Ce0.15CuO4−δ superconductor of different Tc's and transition widths has been studied in the magnetic field parallel to c-axis direction. The characteristic fishtail magnetizations are observed for all samples measured, with the secondary peak field decreasing with decreasing Tc and a corresponding change in the relative peak heights. The critical currents corresponding to the maximum widths in the hysteresis loops increase with decreasing Tc. These results suggest that increased pinning enhances the anomalous magnetization, consistent with a model that the secondary peak is due to a dimensional crossover from 3D to 2D pinning.
