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

Hiroshi Yanagi, Ryuto Kawamura, Toshio Kamiya, Yoichi Kamihara, Masahiro Hirano, Tetsuya Nakamura, Hitoshi Osawa, Hideo Hosono

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Abstract

The electronic and magnetic properties of cobalt-based layered oxypnictides, LaCoOX (X=P,As), are investigated. LaCoOP and LaCoOAs show metallic type conduction with room-temperature resistivities of ∼2× 10-4 Ωcm, 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 with spontaneous magnetic moments of 0.33 μB and 0.39 μB extrapolated to 0 K, respectively. Above the transition temperatures, the magnetic susceptibility exhibits a large temperature dependence. Provided that this temperature dependence follows the Curie-Weiss law, enhanced magnetic-moment values of ∼2.9 μB for LaCoOP and ∼1.3 μB for LaCoOAs are obtained. 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 with a magnetic moment of 0.52 μB, ∼95% of which is localized on the Co ions. These results indicate that LaCoOX are itinerant ferromagnets and suggest that their magnetic properties are governed by spin fluctuation.

Original languageEnglish
Article number224431
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume77
Issue number22
DOIs
Publication statusPublished - 2008 Jun 20
Externally publishedYes

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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