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MA: Fachverband Magnetismus
MA 15: Magnetism Poster A
MA 15.23: Poster
Dienstag, 2. April 2019, 10:00–13:00, Poster E
Surface- and ligand-dependent quenching of the spin magnetic moment of Co porphyrins — Lucas M. Arruda1, Matthias Bernien1, Fabian Nickel1, Nino Hatter1, Lalminthang Kipgen1, C. Felix Hermanns1, Dennis Krüger1, Timo Bißwanger1, Enrico Schierle2, Eugen Weschke2, Katharina J. Franke1, and •Wolfgang Kuch1 — 1Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
The bonding flexibility of metalloporphyrin molecules makes them versatile candidates for spintronic applications. The magnetic properties of these molecules can be readily influenced by changes to their ligands. We investigate the electronic and magnetic properties of cobalt octaethylporphyrin (CoOEP), deposited on two similar surfaces, Cu(100) and Cu(111), with x-ray absorption spectroscopy and x-ray magnetic circular dichroism. A significant magnetic moment is observed from the cobalt ions of the molecules deposited on Cu(100), but it is completely quenched on Cu(111). Subjecting the molecules to an annealing process causes an intramolecular reaction, resulting in cobalt tetrabenzoporphyrin. The new molecules on both substrates have a quenched magnetic moment and similar electronic properties as the CoOEP molecules deposited on Cu(111). We propose that the CoOEP molecules on Cu(100) display an unusual mixed-valence configuration caused by the hybridization of the cobalt ion with the copper substrate, leading to the quench of the cobalt ions' magnetic spin moment.