Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 57: Posters Magnetism II
MA 57.32: Poster
Thursday, March 19, 2020, 15:00–18:00, P3
Light-, temperature-, and x-ray-induced spin-crossover transition of molecules adsorbed on a graphite surface — •Jorge Torres1, Lalminthang Kipgen1, Sascha Ossinger2, Sangeeta Thakur1, Ivar Kumberg1, Rahil Hosseinifar1, Lucas M. Arruda1, Evangelos Golias1, Chen Luo3, Kai Chen3, Florin Radu3, Felix Tuczek2, and Wolfgang Kuch1 — 1Freie Universität Berlin, Institut für Experimentalphysik, Berlin, Germany — 2Christian-Albrechts-Universität zu Kiel, Institut für Anorganische Chemie, Kiel, Germany — 3Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
The octahedral symmetry of the metal-ligand bonds of spin-crossover (SCO) molecules enables them to switch between high-spin (HS) and low-spin (LS) electronic configurations when exposed to light or temperature change. The cooperativity between SCO molecules can be studied from bottom-up growth of submonolayer coverages on well-defined substrates by X-ray absorption spectroscopy (XAS). A 0.4 monolayer coverage of [Fe(H2B(pypz)(pz))2] was deposited on highly oriented pyrolytic graphite and measured by XAS. Analysis of the HS to LS fraction showed that light-induced excited spin-state trapping at 10 K doubles the high-spin fraction compared with the value reached by thermally induced spin-state transition at room temperature. On the other hand, due to the onset of soft-x-ray-induced excited spin-state trapping, the largest amount of LS-state molecules is reached at 60 K, while the transition temperature T1/2 (50% HS and 50% LS) is at 300 K.