Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 49: POSTER II

MA 49.3: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster A

XAS Study of the Spin-Crossover Molecules Fe(bpz)₂phen and Fe(bpz)₂bipy on Surfaces — •Lalminthang Kipgen¹, Holger Naggert², Matthias Bernien¹, Fabian Nickel¹, Jens Kopprasch¹, Qingyu Xu^1,3, Felix Tuczek², and Wolfgang Kuch¹ — ¹Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany — ²Institut für Anorganische Chemie, Christian-Albrechts Universität zu Kiel, 24098 Kiel, Germany — ³Department of Physics, Southeast University, 211189 Nanjing, P.R. China

The Spin-crossover molecules Fe(bpz)₂phen and Fe(bpz)₂bipy (bpz=dihydrobis(pyrazolyl)borate, phen = 1,10-phenanthroline, bipy = 2,2-bipyridine) have recently attracted a lot of attention due to their suitability for vacuum deposition. Thin films and even single molecules on surfaces have been studied. However, if the molecules are in direct contact with another material, their spin-crossover properties may be altered or even suppressed. We have investigated submonolayers of Fe(bpz)₂phen and Fe(bpz)₂bipy on Au(111), Bi(111) and HOPG surfaces by means of X-ray absorption spectroscopy (XAS). We find that submonolayers of Fe(bpz)₂bipy on Au(111) do not exhibit thermal spin-crossover behavior. On HOPG, in contrast, these molecules show complete spin-state switching as a function of temperature. Submonolayers of Fe(bpz)₂phen on Bi(111) show a partial conversion of about 40 percent as a function of temperature and illumination with green light at T = 5 K. Financial support by the DFG (Sfb’s 658 and 677) is gratefully acknowledged.