title: Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO1-xFxFeAs.
abstract: A series of layered CeO1-xFxFeAs compounds with x=0 to 0.20 are synthesized by the solid state reaction method. Similar to the LaOFeAs, the pure CeOFeAs shows a strong resistivity anomaly near 145 K, which was ascribed to the spin-density-wave instability. F doping suppresses this instability and leads to the superconducting ground state. Most surprisingly, the superconducting transition temperature could reach as high as 41 K. Such a high T_{c} strongly challenges the classic BCS theory based on the electron-phonon interaction. The closeness of the superconducting phase to the spin-density-wave instability suggests that the magnetic fluctuation plays a key role in the superconducting pairing mechanism. The study also reveals that the Ce 4f electrons form local moments and are ordered antiferromagnetically below 4 K, which could coexist with superconductivity.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
authors.forename: G F
authors.initials: GF
authors.lastname: Chen
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: G
authors.initials: G
authors.lastname: Li
authors.forename: W Z
authors.initials: WZ
authors.lastname: Hu
authors.forename: J
authors.initials: J
authors.lastname: Dong
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.forename: J L
authors.initials: JL
authors.lastname: Luo
authors.forename: N L
authors.initials: NL
authors.lastname: Wang