Itinerant Ferromagnetism in layered crystals LaCoOX (X = P, As)
  The electronic and magnetic properties of cobalt-based layered oxypnictides, LaCoOX (X = P, As), are investigated. LaCoOP and LaCoOAs show metallic type conduction, and the Fermi edge is observed by hard x-ray photoelectron spectroscopy. Ferromagnetic transitions occur at 43 K for LaCoOP and 66 K for LaCoOAs. Above the transition temperatures, temperature dependence of the magnetic susceptibility follows the Curie-Weiss law. X-ray magnetic circular dichroism (XMCD) is observed at the Co L2,3-edge, but not at the other edges. The calculated electronic structure shows a spin polarized ground state. These results indicate that LaCoOX are itinerant ferromagnets and suggest that their magnetic properties are governed by spin fluctuation. 
Hiroshi Yanagi, Ryuto Kawamura, Toshio Kamiya, Yoichi Kamihara,   Masahiro Hirano, Tetsuya Nakamura, Hitoshi Osawa, Hideo Hosono