Regensburg 2010 – wissenschaftliches Programm
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KR: Fachverband Kristallographie
KR 10: Poster: Multiferroics (with MA, DF, KR, DS)
KR 10.9: Poster
Dienstag, 23. März 2010, 10:45–13:45, Poster A
Magnetic coupling of Co porphyrin molecules to ferromagnetic substrates — •Felix Hermanns, Alexander Krüger, Matthias Bernien, Jorge Miguel, and Wofgang Kuch — Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
Metalorganic compounds are promising candidates for spintronic devices. In this context, the interaction of the central transition metal ion of Fe-octaethyl-porphyrin molecules with underlying ferromagnetic substrates has been studied and found that it can be changed from parallel to antiparallel [1].
Here, we report on X-ray absorption spectroscopy (XAS) measurements of submonolayers of Co-octaethyl-porphyrin on bare and oxygen-covered Ni films grown on Cu(001). By means of angle-dependent XAS measurements at the N K-edge, a parallel orientation of the quasi-planar molecule is found with respect to the surface.
The Co L3,2 XAS and XMCD spectra display significant differences for the two substrates. Angle-dependent spectral changes are explained by the distinct contributions of the individual Co 3d orbitals. The modification of the Co oxidation state by the adsorption on the two substrates is discussed. XMCD investigations yield a ferromagnetic coupling at room temperature between the Ni substrate and the Co ion only in the case of the bare metal surface. From the temperature dependence of the Co-XMCD signal, the magnetic coupling energy is evaluated.
This work is supported by the DFG (Sfb 658).
[1] M. Bernien et al., Phys. Rev. Lett. 102, 047202 (2009)