Continuous 3d Freezing Transition in Layered Superconductors

TL;DR

This paper uses Ginzburg-Landau theory to analyze the continuous transition to a vortex super-solid in layered superconductors, revealing a 3D freezing transition and effects of layering on vortex lattice structure.

Contribution

It introduces a detailed theoretical analysis of the 3D freezing transition in layered superconductors, highlighting the role of layering and Landau level degeneracy.

Findings

Identifies a continuous 3D freezing transition to a vortex super-solid.

Shows local triangular lattice formation due to layering effects.

Discusses the survival of off-diagonal-long-range-order depending on dimensionality.

Abstract

We use Ginzburg-Landau theory to study the $H_{c2}$ transition in layered superconductors with field parallel to the layers, finding a continuous 3d freezing transition to a triangular vortex super-solid in the three-dimensional XY universality class. If screening effects are neglected, off--diagonal--long--range--order survives only for $d>d_{lc}=5/2$. The partial breaking of the lowest Landau level degeneracy induced by layering leads to a {\sl local} selection of a triangular lattice structure, in contrast to the {\sl global} free energy minimization in, e.g. Abrikosov's calculation. Our results are relevant to artificially layered superconductors and to strongly anisotropic high T$_c$ materials.