Magnetic Phase Diagram of Weakly Pinned Type-II Superconductors

TL;DR

This paper reviews the development of the phase diagram for weakly pinned type-II superconductors, highlighting various vortex phases, their properties, and connections to other disordered systems, based on magnetic response studies.

Contribution

It proposes a generic phase diagram for weakly pinned superconductors, including multiple vortex glassy phases and a novel disorder-driven fracturing transition.

Findings

Identification of multiple glassy vortex phases

Evidence of metastability and history dependence in vortex matter

Discovery of a disorder-driven fracturing transition

Abstract

The phenomenon of superconductivity was discovered in 1911, however, the methodology to classify and distinguish type-II superconductivity was established only in late fifties after Abrikosov's prediction of a flux line lattice in 1957. The advent of high temperature superconductors (HTSC) in 1986 focused attention onto identifying and classifying other possible phases of vortex matter in all classes of superconductors by a variety of techniques. We have collated evidences in support of a proposal to construct a generic phase diagram for weakly pinned superconducting systems, based on their responses to ac and dc magnetic fields. The phase diagram comprises quasi-glassy phases, like, the Bragg glass, a vortex glass and a reentrant glass in addition to the (completely) amorphous phases of pinned and unpinned variety. The characteristic metastability and thermomagnetic history dependent features recognized amongst various glassy vortex phases suggest close connections between vortex matter and other disordered condensed matter systems, like, spin glasses, super cooled liquids/ structural glasses, etc. A novel quenched random disorder driven fracturing transition stands out amongst other noteworthy facets of weakly vortex pinned vortex matter.