| Autor: |
Serrate, D., De Teresa, J. M., Algarabel, P. A., Fernández-Pacheco, R., Galibert, J., Ibarra, M. R. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 4/15/2005, Vol. 97 Issue 8, p084317, 6p, 5 Graphs |
| Abstrakt: |
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<120 K) the linear high-field MR disappears. We interpret these results in terms of the grain-boundary properties. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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