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MA: Fachverband Magnetismus
MA 10: Poster I
MA 10.2: Poster
Dienstag, 23. März 2010, 10:45–13:45, Poster A
Magnetic anisotropy of paramagnetic porphyrin molecules on non-magnetic surfaces: an angle-dependent XMCD investigation — •Matthias Bernien1, Jorge Miguel1, Wolfgang Kuch1, Adrian D. Ward Cherrier2, Carsten Tieg2, Claudia Weis3, Carolin Antoniak3, Dietger Bovenschen3, and Heiko Wende3 — 1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin — 2ESRF, BP 220, F-38043 Grenoble Cedex, France — 3AG Wende and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg
Metal complexes on surfaces are a topic of intensive scientific investigations since the properties of their central metal ion, determined by the adjacent ligands, can be widely tuned by the chemical design of the molecule. Here we report on the electronic structure and the magnetic properties of paramagnetic Fe and Co octaethylporphyrin molecules adsorbed on non-magnetic Cu(100) and oxygen-covered (√2×2√2)R45∘ O/Cu(100) surfaces. The magnetic moments of the metal centers of the molecules are aligned by an external magnetic field of 5 T at a temperature of 8 K. The magnetic anisotropy of the metal centers is probed by XMCD measurements along the easy and hard magnetization direction. For Fe porphyrin molecules on the bare Cu(100) substrate a negligible magnetic anisotropy is found. In contrast, a huge magnetic anisotropy of the Fe ion can be obtained by placing half a monolayer of atomic oxygen between the molecules and the Cu(100) surface. This work has been supported by DFG (Sfb 658 and Sfb 491) and ESRF (HE 2700).
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