Ultrathin magnetite inFe3O4/MgOsuperlattices: Investigating the enhanced thin film magnetic moment

The electrical, crystallographic, and magnetic properties of ultrathin magnetite (${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$) have been studied in detail, by employing superlattice structures of ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$/${\mathrm{MgFe}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$/MgO on a variety of substrates. By careful analysis of their properties, the influence of substrate stoichiometry, ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ thin film thickness, antiphase boundaries on the magnetic properties can be separated. In particular, the controversial enhanced magnetic moment in ultrathin films (5 nm) was confirmed to be related to the substrate stoichiometry, specifically the migration of oxygen vacancies into the ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ thin films. The multilayer concept can be employed with many other such systems and offers methods of tuning the properties of thin magnetic oxides.