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

Abstract

A universal phase diagram for weakly pinned low-Tc 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-Tc materials which is independent of the microscopic mechanisms of superconductivity in these systems.