DYNAMIC CHARACTERISTICS OF THE ANOMALOUS 2ND PEAK IN THE MAGNETIZATION CURVES OF BI-SR-CA-CU-O

We present magnetization curves for Bi-Sr-Ca-Cu-O crystals which exhibit an anomalous second peak. Between 20 and 40 K the peak disappears gradually with time. At lower temperatures (18 K) the peak is absent in the short-time limit and it is gradually built up with time. A smooth universal function relates the magnetization at the peak (400 Oe) with that at the minimum (200 Oe) for all isotherms and at any given time, thus demonstrating the absence of the anomalous peak in the short-time limit at all isotherms.