Itinerant ferromagnetism in the layered crystals LaCoOX(X=P,As)

摘要: The electronic and magnetic properties of cobalt-based layered oxypnictides, $\text{LaCoO}X(X=\text{P},\text{As})$, are investigated. LaCoOP LaCoOAs show metallic type conduction with room-temperature resistivities $\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }\ensuremath{\Omega}\text{ }\text{cm}$, the Fermi edge is observed by hard x-ray photoelectron spectroscopy. Ferromagnetic transitions occur at 43 K for 66 spontaneous moments $0.33{\ensuremath{\mu}}_{B}$ $0.39{\ensuremath{\mu}}_{B}$ extrapolated to 0 K, respectively. Above transition temperatures, susceptibility exhibits a large temperature dependence. Provided that this dependence follows Curie-Weiss law, enhanced magnetic-moment values $\ensuremath{\sim}2.9{\ensuremath{\mu}}_{B}$ $\ensuremath{\sim}1.3{\ensuremath{\mu}}_{B}$ obtained. X-ray circular dichroism (XMCD) Co ${L}_{2,3}$ edge, but not other edges. calculated structure shows spin-polarized ground state moment $0.52{\ensuremath{\mu}}_{B}$, $\ensuremath{\sim}95%$ which localized on ions. These results indicate $\text{LaCoO}X$ itinerant ferromagnets suggest their governed spin fluctuation.