Resurrection of the Melting Line in the Bose Glass Superconductor

Abstract

I argue that in contrast to $B<B_ϕ$, where the Vortex Liquid (VL) freezes into the Strongly-pinned Bose Glass phase (SBG), with flux-line vortices localized by the columnar defects, for $B>B_ϕ$, 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 $B>B_ϕ$, 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 $B>B_ϕ$ the true linear superconductor only forms at $T$ well below the $B<B_ϕ$ irreversability line.