Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 59: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth
O 59.12: Vortrag
Mittwoch, 18. März 2015, 17:45–18:00, MA 042
The Structure of Magnetite(100)-c(2×2) revisited — •Lutz Hammer1, Pascal Ferstl1, M.Alexander Schneider1, Roland Bliem2, Ulrike Diebold2, and Gareth Parkinson2 — 1Solid State Physics, FAU Erlangen-Nürnberg — 2Inst. Appl. Physics, TU Wien
The widely accepted "Distorted-Bulk-Truncation" model [1,2] for the c(2×2) surface reconstruction of Fe3O4(100) fails to explain recent STM results for the adsorption and nucleation behaviour of metal adatoms on this surface [3,4]. We have therefore revisited the surface structure by means of a full-dynamical LEED intensity analysis. We tested in particular a new model of subsurface cation vacancies and interstitials [5], which was not yet considered in a former LEED analysis [2]. This new model led to a remarkably better correspondence between experimental and calculated spot intensities expressed by a Pendry R-factor of 0.125 (compared to 0.34 of ref.[2]). The new analysis is based on a very large experimental data base of 11300 eV allowing a safe determination of as much as 59 structural parameters. The atomic coordinates derived from the LEED analysis are in excellent agreement with predictions from DFT for this structure [5]. This study also proves that there are no inherent problems in the LEED I-V methodology to properly determine the structure of oxide surfaces as frequently claimed in literature.
[1] R. Pentcheva et al., PRL 94, 126101 (2005); [2] R. Pentcheva et al., Surf. Sci. 602, 1299 (2008); [3] Z. Novotny et al., PRL 108, 216103 (2013); [4] G.S. Parkinson et al., Nat. Mater. 12, 724 (2013); [5] R. Bliem et al. Science, accepted