Superconductivity induced by co-doping in quaternary fluoroarsenide CaFeAsF.
A new quaternary fluoroarsenide CaFeAsF with the tetragonal ZrCuSiAs-type structure composed of alternate stacking of (FeAs)delta- and (CaF)delta+ layers was synthesized. CaFeAsF is a poor metal and shows the anomaly at approximately 120 K in temperature dependence of electrical conductivity. The electron doping by the partial replacement of the iron with cobalt suppresses the anomaly and induces the bulk superconductivity (optimal Tc = 22 K for CaFe0.9Co0.1AsF), analogous to recently discovered FeAs-based superconductors. The present results suggest that CaFeAsF is a promising candidate as a parent compound for high Tc superconductors.
Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan. satoru@lucid.msl.titech.ac.jp
Satoru
S
Matsuishi
Yasunori
Y
Inoue
Takatoshi
T
Nomura
Hiroshi
H
Yanagi
Masahiro
M
Hirano
Hideo
H
Hosono