Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 75: Poster Session: Transport 1
TT 75.15: Poster
Thursday, March 23, 2017, 15:00–19:00, P2-EG
Resonance phenomena in ferrocene-based single-molecule junctions — •Diana Slawig1, Karthiga Kanthasamy1, Markus Ring3, Holger Butenschön2, Christoph Tegenkamp1, Fabian Pauly3, and Herbert Pfnür1 — 1Inst. f. Festkörperphysik, Leibniz Universität Hannover — 2Inst. f. organ. Chemie, Leibniz Universität Hannover — 3FB Physik, Universität Konstanz
Ferrocene dithiol (FDT) molecules as molecular junctions and switches are particularly attractive because of their high conductance and their rotational flexibility. In our study of electrical transport through single FDT molecules between Au contacts via the break junction technique it turns out that the conductance depends strongly on the chemical end groups. This dependence allows tuning of the energy level alignment of HOMO and LUMO relative to the Fermi energy of the electrodes, as demonstrated by the comparison between ferrocene-1,1′-diamine (FDA) and FDT, making FDT a much better conductor than FDA. Comparison of the experimental results with DFT calculations based on the single level model suggest changes of binding geometries of the molecule at the electrodes as a function of electrode separation for both molecules. Particularly interesting are resonances in the IV-curves of FDT at fixed contact distances in the conductance range (at zero bias) between 0.1 G0 to 0.56 G0. This phenomenon can be described by the Fano resonance model, as verified for selected molecular binding geometries in DFT simulations, which, however yields a too high temperature dependence. Therefore, further possible contributions from inelastic transport processes will also be discussed.