Disordered type-II superconductors: a universal phase diagram for low-T-c 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 g lass" phase is argued to transform first into a disordered, glassy phase up on 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 eff ect regime of 2H-NbSe2 and several other low-T-c materials which is indepen dent of the microscopic mechanisms of superconductivity in these systems. ( C) 2001 Elsevier Science B.V. All rights reserved.