Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 28: Surface Magnetism
MA 28.13: Vortrag
Donnerstag, 29. März 2007, 18:15–18:30, H23
Magnetic ordering and switching of iron porphyrin molecules mediated by ferromagnetic films — •H. Wende1,2, M. Bernien2, J. Luo2, C. Sorg2, N. Ponpandian2, J. Kurde2, J. Miguel2, M. Piantek2, X. Xu2, Ph. Eckhold2, W. Kuch2, K. Baberschke2, P.M. Panchmatia3, B. Sanyal3, P.M. Oppeneer3, and O. Eriksson3 — 1Angewandte Physik, Fachbereich Physik, Universität Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany — 2Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany — 3Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala, Sweden
We studied the structural and magnetic ordering of paramagnetic Fe-based porphyrin molecules on Ni and Co films on Cu(100) by means of X-ray absorption spectroscopy. Angle-dependent NEXAFS spectra at the C and N K-edges reveal that for a coverage of 1 ML the porphyrin molecules lie flat on the surface. With XMCD measurements at the Fe, Co and Ni L2,3 edges we show that the Fe magnetic moment is always aligned parallel to the magnetization of the ferromagnetic layers. This allows to switch the Fe magnetic moment in all four cartesian directions relative to the molecular plane. The experimental results are combined with density functional theory to analyze the nature of the magnetic coupling. Thereby we show that the coupling is not due to a trivial direct exchange between the Fe atom and the Ni or Co films. The dominant mechanism is a 90 degree indirect exchange via the N-ligands yielding a magnetic polarization of the Fe. Supported by BMBF (05 KS4 KEB 5) and DFG (Sfb 658, Heisenberg-Programm).