Grain-boundary magnetoresistance up to 42 T in cold-pressed Fe3O4 nanopowders

The magnetoresistance (MR) in cold-pressed magnetite nanopowders has been studied using pulsed magnetic field up to 42 T and steady field up to 12 T. Ball milling in air produces pure and stoichiometric Fe3O4 grains of nanometric size coated by a thin layer of Fe2O3, which electrically isolates the...

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Bibliographic Details
Published in:Journal of applied physics 2005-04, Vol.97 (8)
Main Authors: Serrate, D., De Teresa, J. M., Algarabel, P. A., Fernández-Pacheco, R., Galibert, J., Ibarra, M. R.
Format: Article
Language:English
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Summary:The magnetoresistance (MR) in cold-pressed magnetite nanopowders has been studied using pulsed magnetic field up to 42 T and steady field up to 12 T. Ball milling in air produces pure and stoichiometric Fe3O4 grains of nanometric size coated by a thin layer of Fe2O3, which electrically isolates the magnetite and acts as a tunnel barrier. Therefore, the intergrain magnetoresistance of magnetite grain boundaries can be analyzed regardless of the bulk transport properties. At high fields and high temperature, the MR depends linearly on the field, whereas at lower fields a direct tunneling contribution governed by the surface magnetization appears. Below the Verwey transition (T
ISSN:0021-8979
1089-7550
DOI:10.1063/1.1868877