The growth of manganese oxide on a Au(111) support has been examined over a wide range of preparation conditions and film thicknesses by means of scanning tunneling microscopy (STM), electron diffraction, and photoelectron spectroscopy. Two oxide polymorphs were found to coexist on the gold surface. Whereas MnO-type structures prevail at oxygenlean preparation conditions, annealing in oxygen gives Hausmannite Mn 3 O 4 as the dominant phase. Both polymorphs adopt square structures that only permit row-matched growth on the hexagonal gold, explaining the high tendency for oxide dewetting at elevated temperature. The manganese oxide films are thus polycrystalline and consist of a large number of submicrometer grains with different orientations and surface terminations. A variety of square and line patterns were identified on top of the oxide crystallites, all of them being compatible with either the primitive 5.8 × 5.8 Å 2 cell of Mn 3 O 4 (001) or an ordered MnO(100) vacancy structure. STM conductance spectroscopy provides insight into the electronic properties of the Mn−O islands and yields the approximate size of the band gap as well as the energy position of localized Mn 3d levels in the gap region. Our work illuminates the structural and electronic properties of manganese oxide films grown on Au(111) and therefore complements earlier studies performed on Pt(111), Pd(100), and Ag(100) supports.

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We investigated the electronic and the structural properties of Mn 3 O 4 thin films grown on Cu(111) as a function of preparation conditions (oxygen partial pressure and thickness). Mn 3 O 4 films are grown at oxygen partial pressure of 5 × 10 −7 mbar and displayed a (110) preferential plane orientation arranged in different spatial domains to better adapt to Cu(111) lattice parameters. The relative angle between the domains varies as the film thickness increases. At the Mn 3 O 4 /Cu(111) interface, the valence band is strongly perturbed by the contribution of Cu 3d states that modify the Mn 3d electronic configuration. As a consequence, Mn 3s and Mn 2p core level spectra present characteristic new line shapes that were explained within the core-level relaxation framework. At variance with other metal substrates used for stabilizing manganese oxides thin films, the copper presents a 3d electronic distribution strongly overlapping the Mn 3d orbital and consequently affecting the overall electronic properties at the contact layer.

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