Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 10: Oxides and insulators II
O 10.3: Vortrag
Montag, 23. März 2009, 15:30–15:45, SCH A01
Long-range ordered manganese oxide bilayer on Pt(111): An in-vivo STM, STS and LEED study at elevated temperatures — •Benjamin Bochmann, Steffen Sachert, Christian Hagendorf, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
Growth as well as atomic structure of ultrathin epitaxial manganese oxide films on Pt(111) have been studied using STM, STS and LEED. The films have been prepared by reactive Mn deposition in an oxygen atmosphere of 10−8 to 10−6 mbar. STM measurements performed during growth (in-vivo) at elevated temperatures (400-600 K) reveal three different well-ordered monolayer structures depending on preparation conditions with MnO, Mn3O4 and MnO2 stoichiometry. Only the MnO monolayer is thermally stable up to 1100 K and long time stable. The others will be reduced slowly by gaseous carbon monoxide. For manganese oxides bilayers, again three different long-range ordered structures are observed depending on the oxygen content similar as in the monolayer. The MnO(001)-like bilayer is less stable than the MnO monolayer. Heating to 780 K in UHV leads to a reorganization of the MnO(001)-like bilayer and the formation of two new uniaxially reconstructed structures with different corrugation heights. All bilayer structures and films up to six layers thickness exhibit characteristic STS spectra in the 1 - 6 eV range.