Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Organic/bio Molecules on Metal Surfaces VI
O 75.2: Vortrag
Donnerstag, 14. März 2013, 16:15–16:30, H38
Tuning the Kondo screening of an Fe-Porphyrin molecule by on-surface ligand modification — •Benjamin W. Heinrich1, Gelavizh Ahmadi1, Valentin Müller1, José I. Pascual1,2, and Katharina J. Franke1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Germany — 2CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
The structure of the organic ligand in metal-organic complexes governs the adsorption on a metal surface, and thereby, the magnetic interaction between the central ion and the conduction electrons. We use Scanning Tunneling Microscopy and Spectroscopy (STM/STS) at 4.5 K to show how the modification of the ligand structure alters the Kondo screening of an Fe-Porphyrin on Au(111). Annealing Fe(II)-Octaethylporphyrin (FeOEP) on Au(111) to temperatures of about 470 K, we step-wise induce an electrocyclic ring closure of the ethyl groups to finally produce Fe-Tetrabenzoporphyrin (FeTBP). In STS, complex features at low energies around the Fermi level result from Kondo screening of the iron ion’s spin. Changes in width and shape show the tuned interaction of the local spin with the conduction electrons depending on the actual chemical structure of the ligand. These results highlight the importance of chemical engineering for controlling the magnetism of single molecules on surfaces.