ANOMALOUS PEAK EFFECT DEDUCED FROM THE TEMPERATURE-DEPENDENCE OF THE MAGNETIZATION IN THE BI2SR2CACU2O8+Y SYSTEM

We obtained a new aspect in the experimental study of the anomalous peak effect: magnetization curves as a function of magnetic field were deduced from the temperature dependence of the magnetization curves. In this method we can utilize the two different flux distributions in the sample corresponding to the two thermal processes: heating the sample in the field after zero-field cooling (ZFC) and cooling it in the field (FC). The ordinary diamagnetic hysteresis curve was obtained from the data observed in the ZFC process, and a new magnetization curve was obtained from the data taken in the FC process. More than two anomalous peaks were observed in the latter process, suggesting the presence of the higher- and sub-harmonics and the fundamental peak. The sample dependence of the anomalous peak field was investigated for the undoped as-grown sample, an oxygen-annealed sample and a Zn-substituted one.