Kosterlitz-Thouless behavior in layered superconductors: the role of the vortex-core energy

TL;DR

This paper investigates how vortex-core energy influences the Kosterlitz-Thouless transition in layered superconductors, revealing that in anisotropic 3D systems, the transition temperature can exceed the 2D KT temperature, with implications for cuprate experiments.

Contribution

It demonstrates that vortex-core energy controls the KT-like transition temperature in anisotropic 3D layered superconductors, extending understanding beyond the 2D case.

Findings

In 3D anisotropic systems, $T_d$ can be higher than $T_{KT}$ due to vortex-core energy.

Vortex-antivortex fluctuations are observable at energy scale $T_d$ in layered superconductors.

Experimental results in cuprates support the theoretical role of vortex-core energy in transition behavior.

Abstract

In layered superconductors with small interlayer Josephson coupling vortex-antivortex phase fluctuations characteristic of quasi two-dimensional (2D) Kosterlitz-Thouless (KT) behavior are expected to be observable at some energy scale $T_d$. While in the 2D case $T_d$ is uniquely identified by the KT temperature $T_{KT}$ where the universal value of the superfluid density is reached, we show that in a generic anisotropic 3D system $T_d$ is controlled by the vortex-core energy, and can be significantly larger than the 2D scale $T_{KT}$. These results are discussed in relation to recent experiments in cuprate superconductors, which represent a typical experimental realization of layered anisotropic superconductors.