Regensburg 2010 – wissenschaftliches Programm

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 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).