High-field breakdown of the superconducting critical state in Bi2Sr2CaCu2Osingle crystals

The critical state in Bi2Sr2CaCu2O single crystals is found to become unsta ble at low temperatures and high magnetic fields. Reproducible and almost p eriodic flux jumps developed at high fields only are qualitatively differen t from those known in conventional superconductors and predicted by existin g models. The breakdown can occur in the regime considered to be stable, wh ich compromises the existing criteria for the potential high-field applicat ions of high-T-c materials.