MAGNETIZATION DECAY AND PINNING ENERGY IN A BSCCO SINGLE-CRYSTAL - A COMPARISON BETWEEN DIFFERENT METHODS OF MEASUREMENT

The magnetization decay in a BSCCO single crystal was measured by two different methods: in the first way the decay is observed in the time after stopping the magnetic field, in the second one various hysteresis loops are performed at different field sweep rate. Using this two methods of measurements we investigate both flux creep regime both the thermally assisted flux flow regime and, in the creep regime, we calculated the energy pinning Uo. The two methods give different values: an explanation for this discrepancy is proposed.