Electronic structure of theFe3O4(111)surface

The surface electronic band structure of thin, well-ordered epitaxial ${\mathrm{Fe}}_3{\mathrm{O}}_4\left(111\right)$ films has been investigated at room temperature by means of angle-resolved photoelectron spectroscopy using synchrotron radiation. In the $\overline{\Gamma }-\overline{M}$ direction of the ${\mathrm{Fe}}_3{\mathrm{O}}_4\left(111\right)$ surface Brillouin zone (SBZ), two types of dispersion states originating from a periodic multilayered structure of iron and oxygen ions, in which ${\mathrm{Fe}}^{2+}$ and ${\mathrm{Fe}}^{3+}$ cations are incorporated into the close-packed $\mathrm{fcc}$ oxygen sublattice, were identified. Oxygen $2p$-derived states at binding energies between 2.5 and $8\mathrm{eV}$ follow a strong, monotonic dispersion extending from $\overline{\Gamma }$ to $\overline{M}$ of the oxygen-sublattice originating SBZ. On the other hand, the iron $3d$-derived states near the Fermi energy show a weak dispersion with a period half of the $\overline{\Gamma }-\overline{M}$ distance of the latter. The surface electronic band structure of the ${\mathrm{Fe}}_3{\mathrm{O}}_4\left(111\right)$ film measured with photoemission is described as composed from matrix-element governed contributions of the oxygen and the iron sublattices which are related to the different symmetries of their SBZs.