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MA: Fachverband Magnetismus

MA 27: Bio- and Molecular Magnetism

MA 27.14: Talk

Thursday, February 28, 2008, 17:45–18:00, EB 202

Fe-porphyrin monolayers on ferromagnetic substrates: Electronic structure and magnetic coupling strength — •Matthias Bernien¹, Xiaoying Xu¹, Jorge Miguel¹, Marten Piantek¹, Philipp Eckhold¹, Jun Luo¹, Julia Kurde¹, Klaus Baberschke¹, Wolfgang Kuch¹, Heiko Wende², and Pankaj Srivastava² — ¹Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany — ²Fachbereich Physik, Experimentalphysik - AG Wende, Universität Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany

Paramagnetic Fe-porphyrin molecules are promising candidates for applications in molecular nano-electronics. A fundamental understanding of the interaction of these molecules with ferromagnetic substrates is essential to realize future functional devices. Here we present systematic x-ray absorption and x-ray magnetic circular dichroism (XMCD) studies on octaethylporphyrin-Fe(III) chloride molecules sublimated onto epitaxially grown Ni and Co films on Cu(100). The fine structures observed in the absorption and dichroic spectra of the Fe-L_2,3 edges are explained in terms of different Fe 3d orbitals probed in angular-dependent measurements. The coverage of Fe-porphyrin molecules is varied from submonolayer to 1.5 monolayer, and measurements were carried out at room as well as at low temperatures. From the temperature dependence of the Fe-XMCD signal, a weaker coupling strength between the Fe atom and the Ni substrate is found as compared to the Co case.