Nernst effect of the new iron-based superconductor LaO$_{1-x}$F$_{x}$FeAs

TL;DR

This study presents the first Nernst effect measurements on LaO$_{1-x}$F$_{x}$FeAs, revealing vortex dynamics and anomalies in the normal state potentially linked to SDW fluctuations, contributing to understanding iron-based superconductor properties.

Contribution

First Nernst effect measurement on LaO$_{1-x}$F$_{x}$FeAs revealing vortex behavior and normal state anomalies related to SDW fluctuations.

Findings

Large vortex-induced Nernst peak below T_c

Normal state Nernst signal is negative and small

Anomalous depression of thermoelectric current between T_c and 50 K

Abstract

We report the first Nernst effect measurement on the new iron-based superconductor LaO$_{1-x}$F$_{x}$FeAs $(x=0.1)$. In the normal state, the Nernst signal is negative and very small. Below $T_{c}$ a large positive peak caused by vortex motion is observed. The flux flowing regime is quite large compared to conventional type-II superconductors. However, a clear deviation of the Nernst signal from normal state background and an anomalous depression of off-diagonal thermoelectric current in the normal state between $T_{c}$ and 50 K are observed. We propose that this anomaly in the normal state Nernst effect could correlate with the SDW fluctuations.