Metastable vortex states in YBa₂Cu₃O_7-δ crystal

Abstract

Magnetization measurements in an untwinned YBa₂Cu₃O_7-δ crystal reveal a range of temperatures and fields for which the magnetization exhibits unusual history-dependent behavior. This range envelopes the transition line, B_ss(T), separating between the vortex quasiordered and disordered phases. The observed history effects indicate that a disordered (quasiordered) vortex state can exist as a metastable state below (above) the B_ss(T) line. The fields, defining the phase transition and the borders of the metastability region, are correlated to sharp features in the magnetization loop.