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Mechanism of grain-boundary magnetoresistance in Fe O films |
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| Authors: | M. Ziese R. Höhne H.C. Semmelhack H. Reckentin N.H. Hong P. Esquinazi |
| Affiliation: | (1) Department of Superconductivity and Magnetism, University of Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany, DE |
| Abstract: | The magnetotransport properties of magnetite films with different microstructures were investigated in order to identify prerequisites for the attainment of a large tunnelling magnetoresistance in polycrystalline samples. Epitaxial films on MgAl2O4, polycrystalline films on Al2O3 and rough MgAl2O4 substrates and a polycrystalline La0.7Ca0.3MnO3 film on MgO were compared. Although grain boundaries induce a large high-field magnetoresistance in magnetite films, the low-field magnetoresistance characteristic for spin-polarized tunnelling was virtually absent in these samples. Two factors might be responsible for this behaviour: (1) grain boundaries in magnetite are conducting and do not form tunnelling barriers and (2) the spin-polarization near grain boundaries is suppressed due to non-stoichiometry. Received 15 April 2002 Published online 13 August 2002 |
| Keywords: | PACS. 72.25.-b Spin polarized transport – 73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects) – 75.70.-i Magnetic properties of thin films, surfaces, and interfaces |
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