Surface anisotropy of iron oxide nanoparticles and slabs from first principles: Influence of coatings and ligands as a test of the Heisenberg model

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:434

Article

Brymora, Katarzyna¹  Calvayrac, Florent¹ 

[1] Loire Le Mans Univ, Univ Bretagne, Inst Mol & Mat Mans, PSC IMMM,CNRS UMR 6283, Av Messiaen, F-72085 Le Mans 9, France

关键词: Surface anisotropy;    Magnetic nanoparticles;    Heisenberg model;    Ab initio;    Functionalization;   

DOI  :  10.1016/j.jmmm.2017.03.034

来源: Elsevier

【 摘 要 】

We performed ab initio computations of the magnetic properties of simple iron oxide clusters and slabs. We considered an iron oxide cluster functionalized by a molecule or glued to a gold cluster of the same size. We also considered a magnetite slab coated by cobalt oxide or a mixture of iron oxide and cobalt oxide. The changes in magnetic behavior were explored using constrained magnetic calculations. A possible value for the surface anisotropy was estimated from the fit of a classical Heisenberg model on ab initio results. The value was found to be compatible with estimations obtained by other means, or inferred from experimental results. The addition of a ligand, coating, or of a metallic nanoparticle to the systems degraded the quality of the description by the Heisenberg Hamiltonian. Proposing a change in the aniso-tropies allowing for the proportion of each transition atom we could get a much better description of the magnetism of series of hybrid cobalt and iron oxide systems. (C) 2017 Elsevier B.V. All rights reserved.

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