Fabrication of Ferromagnetic Ni(111) Nanoparticles Embedded Epitaxially in (Mg,Ni)O Matrix by Reduction of (Mg0.5Ni0.5)O(111) Epitaxial Thin Film

Abstract

The ferromagnetic Ni nanoparticles could be epitaxially dispersed in the (Mg,Ni)O matrix by the oxide reduction. For this purpose, the epitaxial (Mg0.5Ni0.5)O thin film was grown at room temperature by pulsed laser deposition and successively reduced at 700 °C in hydrogen gas atmosphere. X-ray diffraction confirmed in-plane and out-of-plane epitaxial precipitation of Ni nanoparticles in the (Mg,Ni)O matrix by selective reduction of the Ni–O part in the epitaxial (Mg0.5Ni0.5)O thin film. Atomic-scale analyses indicated uniform dispersion of Ni nanoparticles (∼20 nm average size) in the (Mg,Ni)O matrix. Magnetic measurement confirmed ferromagnetic property of the Ni nanoparticle-containing (Mg,Ni)O thin films.