Competing Orders and Spin-Density-Wave Instability in La(O$_{1-x}$F$_x$)FeAs

TL;DR

This paper investigates the interplay of competing orders in La(O$_{1-x}$F$_x$)FeAs, revealing that spin-density-wave instability is suppressed by electron doping, leading to superconductivity, thus highlighting the complex phase competition in this layered compound.

Contribution

It provides combined experimental and theoretical evidence linking SDW instability suppression to electron doping-induced superconductivity in La(O$_{1-x}$F$_x$)FeAs.

Findings

SDW instability causes anomaly near 150 K in LaOFeAs

Electron doping suppresses SDW and induces superconductivity

La(O$_{1-x}$F$_x$)FeAs exhibits competing orders in layered materials

Abstract

The interplay between different ordered phases, such as superconducting, charge or spin ordered phases, is of central interest in condensed matter physics. The very recent discovery of superconductivity with a remarkable T$_c$= 26 K in Fe-based oxypnictide La(O$_{1-x}$F$_x$)FeAs is a surprise to the scientific community\cite{Kamihara08}. The pure LaOFeAs itself is not superconducting but shows an anomaly near 150 K in both resistivity and dc magnetic susceptibility. Here we provide combined experimental and theoretical evidences showing that the anomaly is caused by the spin-density-wave (SDW) instability, and electron-doping by F suppresses the SDW instability and recovers the superconductivity. Therefore, the La(O$_{1-x}$F$_x$)FeAs offers an exciting new system showing competing orders in layered compounds.