%0 Journal Article
%A Garcia March, M. A.
%A Jimenez Villacorta, F.
%A Quesada, A.
%A de la Venta, J.
%A Carmona Tejero, Noemí
%A Lorite, I.
%A LLopis, J.
%A Fernández, J. F.
%T Surface magnetism in ZnO/Co_3O_4 mixtures
%D 2010
%@ 0021-8979
%U https://hdl.handle.net/20.500.14352/44716
%X We recently reported the observation of room temperature ferromagnetism in mixtures of ZnO and Co_3O_4 despite the diamagnetic and antiferromagnetic character of these oxides, respectively. Here, we present a detailed study on the electronic structure of this material in order to account for the unexpected ferromagnetism. Electrostatic interactions between both oxides lead to a dispersion of Co_3O_4 particles over the surface of ZnO larger ones. As a consequence, the reduction Co^(+3) -> Co^(2+) at the particle surface takes place as evidenced by x-ray absorption spectroscopy measurements and optical spectroscopy. This reduction allows explaining the observed ferromagnetic signal within the well established theories of magnetism in oxides.
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