Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 77: Oxides and insulators: Epitaxy and growth
O 77.10: Vortrag
Donnerstag, 25. März 2010, 17:15–17:30, H42
The surface termination of Mn3O4(001) films on Ag(001) — Michael Huth, •Klaus Meinel, Roman Shantyr, Sebastian Polzin, Konrad Gillmeister, Henning Neddermeyer, and Wolf Widdra — Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Germany
Spinel-like Mn3O4(001) films can be imagined as an alternating stacking of (2x1)-like Mn2O4 and (2x2)-like Mn spinel sublayers (SL). According theory [1], the Mn2O4 layer is favored for termination. In our investigations, Mn3O4 films have been grown on Ag(001) and analyzed by means of STM and SPA-LEED. The films grow with the lattice vectors of the Mn3O4(001) structure aligned along the [110]-like directions of the Ag(001) substrate. This specific film orientation implies an almost vanishing misfit which explains the brilliancy of the LEED spots. In the submonolayer stage, Mn3O4 islands are formed displaying either (2x1) or (2x2) surface termination depending on local thickness. For ultrathin continuous films, a (2x1) termination is resolved. However, for film thickness > 12 spinel SL, SPA-LEED yields a (2x2) pattern. STM shows that the films are nevertheless terminated by a Mn2O4 layer. But it is now composed not only by (2x1) domains but also by domains where the Mn ions form a c(2x2) pattern. The combination of both structures explains the observed (2x2) LEED pattern. The spreading of this more symmetric structure implies a decrease of density of (2x1) domain boundaries and a corresponding decrease of domain boundary energy.
[1] V. Bayer et al., Phys. Rev. B76 (2007) 165428