Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Abstract

A general phenomenology for phase behaviour in the mixed phase of type-II superconductors with weak point pinning disorder is outlined. We propose that the "Bragg glass" phase generically transforms via two separate thermodynamic phase transitions into a disordered liquid on increasing the temperature. The first transition is into a glassy phase, topologically disordered at the largest length scales; current evidence suggests that it lacks the longranged phase correlations expected of a "vortex glass". This phase has a significant degree of short-ranged translational order, unlike the disordered liquid, but no quasi-long range order, in contrast to the Bragg glass. This glassy phase, which we call a "multi-domain glass", is confined to a narrow sliver at intermediate fields, but broadens out both for much larger and much smaller field values. The multi-domain glass may be a "hexatic glass"; alternatively, its glassy properties may originate in the replica symmetry breaking envisaged in recent theories of the structural glass transition. Estimates for translational correlation lengths in the multi-domain glass indicate that * Email:menon@imsc.ernet.in 1 they can be far larger than the interline spacing for weak disorder, suggesting a plausible mechanism by which signals of a two-step transition can be obscured. Calculations of the Bragg glass-multi-domain glass and the multidomain glass-disordered liquid phase boundaries are presented and compared to experimental data. We argue that these proposals provide a unified picture of the available experimental data on both high-T c and low-T c materials, simulations and current theoretical understanding.

Orientational correlations in fluids with quenched disorder

“…Translational invariance is broken 1 in systems with quenched disorder that is distributed inhomogeneously in space [2][3][4] . Novel equal-time correlations 5 , otherwise trivial in the pure system, emerge as a result 6 .…”

Paramagnetic Meissner effect and related dynamical phenomena

“…Recently, it has been proposed that low-T c materials would be better captured by a phase diagram different from what proposed in Fig. 32 [233]. Namely, instead of the vortex glass phase the so called multi-domain glass would intervene between Bragg glass and disordered liquid phase.…”

Muon-Spin Rotation Measurements of an Unusual Vortex-Glass Phase in the Layered SuperconductorBi2.15Sr1.85CaCu2O8+δHeron1, Ray2, Lister3 et al. 2013Phys. Rev. Lett.14080View full textAdd to dashboardCite

“…Magnetic fields penetrate the bulk of a type-II superconductor in the form of quantized vortex lines, which can exhibit several phases [1][2][3]. Among the most studied of these superconductors is the classic anisotropic superconductor Bi 2:15 Sr 1:85 CaCu 2 O 8þ (Bi2212), whose phases have been extensively described both theoretically [1,2,4,5] and experimentally [6][7][8][9][10][11][12].…”

“…For periodic vortex correlations, subject to small amounts of disorder, there exist a number of analytic models to adequately describe the data in either the time or frequency domain [17]. For nontrivial correlations, Monte Carlo or other numerical approaches may be used to model the detailed shape of pðBÞ [3,12,18].…”

“…The nature of the vortex state in the region that surrounds the vortex lattice phase has long been the source of much experimental [6][7][8][9][10][11][12] and theoretical debate [1][2][3]5,10,11,18]. This region has proved notoriously difficult to equilibrate via numerical simulations [5,22,23].…”