Superconducting properties of Fe-based layered superconductor LaO$_{0.9}$F$_{0.1-\delta}$FeAs

TL;DR

This paper reports the synthesis of a new Fe-based superconductor LaO$_{0.9}$F$_{0.1- extdelta}$FeAs with superconductivity above 20 K, high critical fields, and evidence of a superconducting gap, highlighting its potential for high-field applications.

Contribution

The paper introduces a new synthesis route for LaOFeAs superconductor with detailed characterization of its superconducting properties and electronic structure.

Findings

Superconductivity above 20 K confirmed in LaO$_{0.9}$F$_{0.1- extdelta}$FeAs.

High upper critical field of about 54 T observed.

Superconducting gap signature detected in infrared spectra.

Abstract

We have employed a new route to synthesize single phase F-doped LaOFeAs compound and confirmed the superconductivity above 20 K in this Fe-based system. We show that the new superconductor has a rather high upper critical field of about 54 T. A clear signature of superconducting gap opening below T$_c$ was observed in the far-infrared reflectance spectra, with 2$\Delta/\textit{k}T_c\approx$3.5-4.2. Furthermore, we show that the new superconductor has electron-type conducting carrier with a rather low carrier density.