Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 30: Electronic structure of Surfaces: Magnetism and Spin Phenomena

MA 30.5: Poster

Tuesday, March 21, 2017, 18:30–20:30, P1A

Inelastic Excitations on Fe-TPyP on Au(111) — •Daniela Rolf, Christian Lotze, Benjamin W. Heinrich, and Katharina J. Franke — Freie Universität Berlin

Prophyrin molecules constitute a class of well-investigated molecules, due to their versatility in terms of self-assembly and electronic and magnetic properties. Numerous studies have been performed with different central metal atoms on different metal surfaces, showing that by a suitable choice of metal center and surface, the molecular properties can be tailored. Interesting phenomena were observed, including the Kondo effect, vibronic coupling and negative-differential resistance.

Here, Fe-tetra-pyridil-porphyrin (Fe-TPyP) molecules were investigated on a Au(111) substrate. Employing a low-temperature STM, we show that a multitude of steps in the dI/dV-signal up to 135meV can be observed symmetrically around the Fermi level. These inelastic excitations were observed both on the Fe-center of the molecule as well as on the organic TPyP ligand, with some of the steps on the ligand being visible only at positive bias polarity. As none of the inelastic excitations could be observed on chlorine-coordinated Fe-TPyP-Cl molecules, molecular vibrations were excluded as the origin of the inelastic excitations. Instead, a contribution of magnetic origin is assumed.