Influence of substrate pre-deposition annealing on step edges-induced magnetoresistance in epitaxial magnetite films grown on vicinal MgO (1 0 0) substrates

Magnetoresistance (MR) properties of epitaxial magnetite, Fe 3O 4, films grown on vicinal MgO (1 0 0) substrates show an enhancement and anisotropy in the MR in the direction across the step edges compared to the direction along the step edges. The observed enhancement in low-field MR response and M...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2007-09, Vol.316 (2), p.e969-e972
Main Authors: Sofin, R.G.S., Arora, S.K., Shvets, I.V.
Format: Article
Language:English
Subjects:
Magnetoresistance
Molecular beam epitaxy
Thin film
Verwey transition
Vicinal substrate
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Summary:Magnetoresistance (MR) properties of epitaxial magnetite, Fe 3O 4, films grown on vicinal MgO (1 0 0) substrates show an enhancement and anisotropy in the MR in the direction across the step edges compared to the direction along the step edges. The observed enhancement in low-field MR response and MR anisotropy of epitaxial Fe 3O 4 films is explained by the enhanced spin scattering introduced due to the presence of atomic height steps, which leads to the formation of a greater number of antiphase boundaries (APBs) with out-of-plane shift vectors. We found that the optimum annealing duration required to observe maximum MR anisotropy is between 5 and 9 h. Longer annealing time leads to segregation of Ca impurities on the MgO surface which lead to a decrease in APB density and MR anisotropy.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2007.03.158