Resurrection of the Melting Line in the Bose Glass Superconductor

TL;DR

This paper proposes a new phase diagram for vortex matter in Bose glass superconductors, revealing a crossover from vortex liquid to interstitial liquid and a weakly-pinned Bose glass at high magnetic fields, affecting the superconductor's linear response.

Contribution

It introduces a novel understanding of vortex phases above the matching field, including the interstitial liquid and weakly-pinned Bose glass, contrasting previous models.

Findings

Identification of a sharp crossover to the interstitial liquid phase for B > B_phi.

Discovery of a weakly-pinned Bose glass phase at lower temperatures.

Implication that true linear superconductivity occurs only at low temperatures above B_phi.

Abstract

I argue that in contrast to $B<B_\phi$, where the Vortex Liquid (VL) freezes into the Strongly-pinned Bose Glass phase (SBG), with flux-line vortices localized by the columnar defects, for $B>B_\phi$, the additional vortices see a significantly weaker random $z$-independent potential due to the caging by the vortices strongly pinned on the columnar defects. The result is that for $B>B_\phi$, upon cooling, the VL undergoes a sharp crossover to the Interstitial Liquid (IL) where SBG coexists with a resistive liquid of interstitial vortices. At lower $T$ the IL freezes into a distinct Weakly-pinned Bose Glass phase (WBG). Therefore for $B>B_\phi$ the true linear superconductor only forms at $T$ well below the $B<B_\phi$ irreversability line.