Preparation, structure, and electronic properties ofFe3O4films on theFe(110)/Mo(110)/Al2O3(112¯0)substrate

Abstract

The surface and interface structure as well as the electronic properties of thin epitaxial ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ films prepared by in situ oxidation of thin Fe(110) films grown on ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(112\ifmmode\bar\else\textasciimacron\fi{}0)$ substrates using a Mo(110) buffer layer were investigated by low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and spin-polarized angle-resolved photoemission spectroscopy (SPARPES). The annealing of Fe(110) films at 700 \ifmmode^\circ\else\textdegree\fi{}C in an ${\mathrm{O}}_{2}$ atmosphere leads to the formation of epitaxial ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ films. Atomically resolved STM images of the ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ surface show a hexagonal symmetry with 6 \AA{} periodicity. Well-controlled interface properties at the ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)/\mathrm{Fe}(110)$ and Fe(110)/Mo(110) interfaces were confirmed by TEM. A high spin polarization value of about $\ensuremath{-}(60\ifmmode\pm\else\textpm\fi{}5)%$ was found near the Fermi energy ${E}_{F}$ at room temperature by means of SPARPES with a photon energy of $h\ensuremath{\nu}=21.2\mathrm{eV}.$ The electronic structure and spin polarization are compared to the corresponding values recently found on epitaxial ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ films grown on W(110) single-crystal substrates.