Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 14: Bio- and Molecular Magnetism
MA 14.2: Vortrag
Dienstag, 1. April 2014, 09:45–10:00, HSZ 401
Interaction of FeP and FePc with magnetic surfaces: adsorption structures, magnetic coupling and spin manipulation — •Barbara Brena1, Heike Herper1, Sumanta Bhandary1, David Klar2, Heiko Wende2, Olle Eriksson1, and Biplab Sanyal1 — 1Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden — 2Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstraße 1, D-47048 Duisburg, Germany
The interaction of organic molecules like porphyrins and phthalocyanines containing divalent 3d transition metals with magnetic substrates provides a possible mechanism of magnetic switching. We have studied the chemisorption of Fe porphyrins (FeP) and of Fe phthalocyanines (FePc) on Co(001) by means of Density Functional Theory with the GGA+U method, including van der Waals dispersion forces. Two different adsorption mechanisms were identified for the two molecules. In both cases a ferromagnetic coupling with the surface was observed, but while the FePc’s maintain a magnetic moment of about 2 µB, close to the gas phase value, the magnetic moment of the FeP’s is increased up to about 4 µB. The change to high spin (S=2) in FeP is driven by the stretching of the Fe-N molecular bonds to more than 2.04 Å, due to the strong chemical interaction with the substrate. The same results have been obtained for FeP chemisorbed on Ni(001), Ni(110) and Ni(111). Fe L edge and N K edge experimental absorption spectroscopy results confirm our theoretical findings related to the magnetic coupling and to the adsorption structure of the molecules.