A scanning tunneling microscopy investigation of MBE-grown Fe3O4(001)

We present STM images of Fe3O4 epitaxially grown on MgO(001) showing details of the surface structure including the surface reconstructions, the presence of monolayer steps on the surface, and the terrace widths. The p(1 x 1) surface is formed by a grouping of 2 to 4 atoms in the unit cell, to form a cluster that is elongated along a [110] direction. Stacking fault defects are revealed by 90 degrees rotations of the surface reconstruction orientation observed on a single terrace, and by the presence of bands devoid of the surface reconstruction separating the regions of different surface reconstruction orientation. Although the oxygen atom positions in MgO and Fe3O4 are lattice matched to within 0.3%, the difference in symmetry of the Fe and Mg atoms leads directly to these faults.