Influence of substrate pre-deposition annealing on step edges-induced magnetoresistance in epitaxial magnetite films grown on vicinal MgO (100) substrates

Abstract Magnetoresistance (MR) properties of epitaxial magnetite, Fe 3 O 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 3 O 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.