Supercooling of the disordered vortex lattice in Bi2Sr2CaCu2O8+δ

Time-resolved local induction measurements near the vortex lattice order-disorder transition in optimally doped Bi2Sr2CaCu2O8+delta crystals show that the high-field, disordered phase can be quenched to fields as low as half the transition field. Over an important range of fields, the electrodyamical behavior of the vortex system is governed by the coexistence of ordered and disordered vortex phases in the sample. We interpret the results as supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the "second magnetization peak.".