Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 3: Bio- and Molecular Magnetism

MA 3.1: Vortrag

Montag, 26. März 2012, 09:30–09:45, EB 202

Influence of an intermediate oxygen layer on the magnetic and electronic properties of Fe and Co porphyrin molecules on Cu(001) — •Heike C. Herper^{1, 3}, Matthias Bernien², Claudia Weis¹, Carolin Antoniak¹, Bernhard Krumme¹, Jorge Miguel², Sumanta Bhandary³, Biplab Sanyal³, Dietger Bovenschen¹, Olle Eriksson³, Peter Entel¹, Wolfgang Kuch², and Heiko Wende¹ — ¹Faculty of Physics and CeNIDE, University of Duisburg-Essen, 47048 Duisburg — ²Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin — ³Department of Physics and Astronomy, Uppsala University, 75120 Uppsala

The ongoing miniaturization of magnetic devices requires the search for new materials, e.g. functional molecules on surfaces. Here, the influence of an intermediate oxygen layer on Cu(001) on the magnetic properties of Fe and Co octaethylporphyrin (OEP) molecules is studied. We have performed a combined study of X-ray absorption spectroscopy (XAS) and density functional theory calculations within the GGA+U method. The calculations reveal that Fe and Co OEP prefer Cu hollow site positions on the oxygen covered surface with an intermediate spin state. The XAS of Co OEP shows a detailed fine structure at the L₃ edge depending on the photon incidence angle. This can be related to the calculated density of states and the occupation of d orbitals with different symmetry. We also investigated the magnetic anisotropy in terms of 2nd order perturbation theory to understand the strong angular dependence of the magnetic dichroic signal of Fe OEP in presence of the oxygen layer. Supported through SFB 491 and SFB 658.