Metastability line in BSCCO phase diagram

Nonlinear charge transport in the low temperature vortex glass state of single crystal Bi2Sr2CaCu2O8 superconductor has been investigated with fast current pulses driven along the ab plane. Field cooled (FC) preparation shows a higher threshold current than zero field cooled (ZFC) one, but is found to be metastable and convertible to the ZFC response by a small field excursion. The metastability appears on the low temperature side of the peak in the temperature dependence of the ZFC threshold current. It is suggested that the onset of metastabilitysignals a new thermodynamic ground state