The magnetoresistance (MR) behavior of epitaxial magnetite ${\mathrm{Fe}}_3{\mathrm{O}}_4$ grown on low-vicinal (small miscut) and high-vicinal (large miscut) MgO substrates is compared. Magnetization measurements on ${\mathrm{Fe}}_3{\mathrm{O}}_4$ films on high-vicinal substrates showed reduced magnetic moment as compared with the films grown on low-vicinal MgO, which correlates well with the expected reduction in magnetic moment due to step edge induced additional antiphase boundaries (APBs) with out-of-plane shift vectors. The MR is significantly higher (12.3% at $2\mathrm{T}$) for a $45\mathrm{nm}$ ${\mathrm{Fe}}_3{\mathrm{O}}_4$ film on high-vicinal substrate than that observed (7.2% at $2\mathrm{T}$) for a film on low-vicinal substrate. A strong anisotropy in the MR is observed in correlation with the direction of atomic step edges. In addition to the increase in MR, the field dependency of the MR is also modified. The observed modification in the magnetotransport behavior of epitaxial ${\mathrm{Fe}}_3{\mathrm{O}}_4$ films is attributed to an enhanced spin scattering arising due to the presence of atomic height steps that lead to the formation of a greater density of antiferromagnetically coupled APBs.

• Received 2 February 2005

DOI:https://doi.org/10.1103/PhysRevB.72.134404