Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 3: Ultrafast Electron and spin dynamics at interfaces I

O 3.10: Talk

Monday, March 12, 2018, 12:45–13:00, MA 005

Direct observation of magnetite surface dynamics by Fast Scanning Tunneling Microscopy — Barbara A. J Lechner, Alexander Bourgund, Ueli Heiz, and •Friedrich Esch — Department of Chemistry & Catalysis Research Center, Technical University of Munich, Lichtenbergstr. 4, D-85748 Garching

Magnetite shows a rich surface chemistry and is a well-known particle support in catalysis [1]. While its surface dynamics have been studied extensively with conventional STM and other techniques [1-3], little is known about these surface processes when studied at the atomic scale at elevated temperatures, with the required high temporal resolution. We present results on the Fe3O4(001) surface dynamics taken with a specially developed FastSTM add-on module [4] that boosts the temporal resolution of our commercial STM up to 12 frames/s, demonstrating the potential of this technique: Surface species and defects that appear similar topographically unravel their different dynamic behavior when increasing temperature stepwise (up to 800 K). In particular, we follow the mobility of H adatoms and of domain boundaries, we observe the subsurface diffusion of Fe atoms and their exchange with the bulk and provide additional insight into the high-temperature transition [3]. Furthermore, the surface morphology is studied under reducing or wet conditions, as well as in an oxygen atmosphere.

References [1] G. S. Parkinson, Surf. Sci. Rep. 2016, 71, 272. [2] R. Bliem et al., Angew. Chem. Int. Ed. 2015, 54, 13999. [3] N. C. Bartelt et al., Phys. Rev. B 2013, 88. [4] F. Esch et al., Rev. Sci. Instrum. 2011, 82, 53702 and NFFA project JRA1.