A vortex dynamics approach to the Nernst effect in fluctuating superconductors

TL;DR

This paper introduces a vortex-based method to analyze the Nernst effect in fluctuating superconductors, revealing how vortex parameters influence diamagnetism and thermoelectric responses above the transition temperature.

Contribution

It presents a novel vortex dynamics approach that allows tuning vortex parameters to study their effects on superconducting fluctuations and thermoelectric properties.

Findings

Diamagnetic response persists above the transition temperature.

Transverse thermoelectric conductivity $oldsymbol{ ext{α}_{xy}}$ tracks magnetization.

Increasing vortex core energy enhances diamagnetism and $ ext{α}_{xy}$.

Abstract

We present a new method to study the Nernst effect and diamagetism of an extreme type-II superconductor dominated by phase fluctuations. We work directly with vortex variables and our method allows us to tune vortex parameters (e.g., core energy and number of vortex species). We find that diamagnetic response and transverse thermoelectric conductivity ($\alpha_{xy}$) persist well above the Kosterlitz-Thouless transition temperature, and become more pronounced as the vortex core energy is increased. However, they \textit{weaken} as the number of internal vortex states are increased. We find that $\alpha_{xy}$ closely tracks the magnetization $(-M/T)$ over a wide range of parameters.