Adsorption of Gold on an Iron-Rich Fe3O4(001) Surface

Depending on the preparation recipe the Fe3O4(001) surface of epitaxial magnetite films on MgO(001) can be stabilized as an oxygen-rich or iron-rich surface. The present study reports the adsorption of gold in a coverage range from submonolayers to several monolayers on the Fe-rich Fe3O4(001) surface with the (root 2 x root 2)R45 degrees reconstruction, which is terminated by Fe dimers. The surface atomic structure was refined and interpreted based on the atomically resolved scanning tunneling microscopy (STM) images. For submonolayer coverage, single Au atoms were found to be stable at room temperature, and from the STM analysis, the atomic Au adsorption sites were identified at the Fe dimers. Eventually, for the multilayer films, the Au adsorbate follows an epitaxial layer-by-layer growth, and the resulting Au films expose the (111) face.