Magnetic behavior of BSCCO and R123 in the vortex liquid state

Detailed measurements of the temperature dependence of the magnetization of BSCCO and R123 has been carried out with a SQUID magnetometer in applied m agnetic field (H parallel toc) ranging between 1 mT and 7 T. In both system s, we observed an anomaly, namely a clear step, just above the irreversibil ity temperature (T-irr) in a reversible magnetization curve. It is also fou nd that this anomalous second step is only observed in a high magnetic fiel d region. Comparative study of both systems suggested that the step is like ly to be caused by different origins. (C) 2001 Elsevier Science B.V. All ri ghts reserved.