LiFeAs: An intrinsic FeAs-based superconductor with Tc = 18 K

Abstract

The synthesis and properties of LiFeAs, a high- Tc Fe-based superconducting stoichiometric compound, are reported. Single crystal x-ray studies reveal that it crystallizes in the tetragonal PbFCl type (P4/nmm) with a=3.7914 (7) Å and c=6.364 (2) Å. Unlike the known isoelectronic undoped intrinsic FeAs compounds, LiFeAs does not show any spin-density wave behavior but exhibits superconductivity at ambient pressures without chemical doping. It exhibits a respectable transition temperature of Tc =18 K with electronlike carriers and a very high critical field, Hc2 (0) >80 T. LiFeAs appears to be the chemical equivalent of the infinite layered compound of the high- Tc cuprates. © 2008 The American Physical Society.