Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: POSTER Ia

MA 19.20: Poster

Dienstag, 17. März 2015, 09:30–13:00, Poster A

Correlation between the magnetic properties of a carboxylic acid and its coordination to a metal surface: An paramagnetic and ferromagnetic resonance (EPR/FMR) study — •S. Masur, T. Marzi, S. Liébana Viñas, R. Meckenstock, and M. Farle — Faculty of Physics, University of Duisburg-Essen, Germany

To get stable mono-disperse and artificially shaped magnetic nanoparticles carboxylic acids are often used. While studying the static and dynamic magnetic properties of the single crystalline Fe₂O₃ nanoparticles by FMR the interface to the carboxyl group provides a paramagnetic center that can be influenced by the FMR signal. The same paramagnetic center is found at the interface of carboxylic acids and Ag nanoparticles. Therefore this type of paramagnetic active interfaces are perfect candidates for monitoring spin transport properties through those interfaces. Here we characterize the principal behavior of these EPR interfaces. Oleic acid gets chemisorbed as a carboxylate, leading to the formation of two covalent COO- bonds and a delocalized electron. Covering a substrate with a monolayer of this cubic Fe₂O₃ nanoparticles (all cubes have a (001) direction perpendicular to the substrate and are randomly oriented in plane) and performing an angle dependent EPR from in-plane to out-of-plane a fourfold anisotropy in the EPR-signal is observed, which is not visible for a pure in-plane EPR. This indicates that the hard direction of the g-tensor of the carboxyl Fe₂O₃ interface is correlated with the [111]-cube-direction. This Effect was further investigated on oxidized Iron-films layered with oleic acid.