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.
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Received 15 April 2002 Published online 13 August 2002
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Ziese, M., Höhne, R., Semmelhack, H. et al. Mechanism of grain-boundary magnetoresistance in Fe O films. Eur. Phys. J. B 28, 415–422 (2002). https://doi.org/10.1140/epjb/e2002-00245-3
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DOI: https://doi.org/10.1140/epjb/e2002-00245-3