Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Hauptvortrag Pentcheva

O 29.1: Hauptvortrag

Donnerstag, 11. März 2004, 09:30–10:15, H36

Beyond the (p=0 Pa, T=0 K) limit: Surface Phase Diagrams and Growth Kinetics from First Principles — •Rossitza Pentcheva — Section Crystallography, Dept. for Earth and Environmental Sciences, LMU München — Fritz-Haber-Institut der MPG, Berlin

Combining density functional theory (DFT) with methods from statistical mechanics (ab initio kinetic Monte Carlo (kMC)) or thermodynamics (ab initio atomistic thermodynamics, see e.g. [1]) enables us to extend the predictive power of DFT to meso- and macroscopic length scales and/or to finite pressures and temperatures. Two examples for their application are presented: In the initial growth of Co on Cu(001) DFT-kMC simulations reveal that the activation of atomic exchange leads to substantial deviations from the predictions of standard nucleation theory, namely a bimodal growth mode and a nonmonotonic scaling behavior of island density [2]. Using ab initio atomistic thermodynamics we construct a phase diagram of Fe3O4(001), a promising material for the development of spintronic devices. A hitherto ignored termination with octahedral iron and oxygen forming a wave-like structure along the [110]-direction is identified as the lowest energy configuration over a broad range of oxygen pressures. The stabilization of the Fe3O4(001)-surface goes together with significant changes in the electronic and magnetic properties, e.g. a halfmetal-to-metal transition. [1] K. Reuter and M. Scheffler, Phys. Rev. B 65, 035406, (2002). [2] R. Pentcheva et al., Phys. Rev. Lett. 90, 076101 (2003). (in collab. with M. Scheffler and W. Moritz; DFG support, PE 883)

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