Superconducting properties of the Fe-based layered superconductor LaFeAsO0.9F0.1-delta

Phys Rev Lett. 2008 Aug 1;101(5):057007. doi: 10.1103/PhysRevLett.101.057007. Epub 2008 Jul 31.

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 over 50 T. A clear signature of superconducting gap opening below T(c) was observed in the far-infrared reflectance spectra, with 2Delta/kT(c) approximately 3.5-4.2. Furthermore, we show that the new superconductor has electron-type conducting carriers with a rather low-carrier density.