Disordered type-II superconductors:: a universal phase diagram for low-Tc systems

A universal phase diagram for weakly pinned low-T-c type-II superconductors is revisited and extended with new proposals. The low-temperature Bragg glass phase is argued to transform first into a disordered, glassy phase upon heating. This glassy phase, a continuation of the high-field equilibrium vortex glass phase, then melts at higher temperatures into a liquid. This proposal provides an explanation for the anomalies observed in the peak effect regime of 2H-NbSe2 and several other low-T-c materials which is independent of the microscopic mechanisms of superconductivity in these systems. (C) 2001 Elsevier Science B.V. All rights reserved.