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X. Zhao, G. Kastlunger, R. Stadler:
"QI effects in electron transport through single molecule Junctions with branches containing ferrocene";
Poster: ELECMOL16 - 8th International Conference on Molecular Electronics, Paris, Frankreich; 22.08.2016 - 26.08.2016.

Quantum interference (QI) effects have been found to significantly reduce the conductance in some single molecule junctions containing conjugated π systems where graphical rules could be derived to predict their occurrence from the molecular structure [1,2]. QI effects could be applied for logical gates[3] and data storage [4] in single molecule electronics, and have been suggested as a general tool
for the implementation of various single molecule devices. In this contribution, the emphasis is on investigating QI effects in molecules containing Ferrocene, where the transmission functions describing coherent electron transport through the junction were calculated from density functional theory in combination with a non-equilibrium Green's function approach (NEGF-DFT). We designed molecular compounds with one and two branches (Fig. 1(a)), where from the transmission functions (Fig. 1(b)) we could identify a QI induced minimum in the energy region of the molecular LUMO, which occur for structures A and C but not for B and D. We used Larsson's formula[5,6] to analyse the cause of this interference effect and further interpret its sources in the respective of molecular and electronic structures. Furthermore, we adjusted the redox state of one of the metal centers for the double-branched compounds by adding a Chlorine atom into the junction which subtracted an electron from the junction due to its high electronegativity, where we achieved
an asymmetry of the two branches regarding their respective partial charges to different degrees by gradually changing the distance between the Chlorine atom and one of the two Ferrocene groups.

References:
[1] T. Markussen, R. Stadler, K. S. Thygesen, Nano Lett., 10, 4260-4265, 2010.
[2] R. Stadler, Nano Lett., 15, 7175-7176, 2015.
[3] R. Stadler, S. Ami, M. Forshaw and C. Joachim, Nanotechnology 15, S115-S121, 2004.
[4] R. Stadler, M. Forshaw and C. Joachim, Nanotechnology 14, 138-142, 2003.
[5] A. A. Voityuk, Phys. Chem. Chem. Phys., 14, 13789-13793, 2012.
[6] G. Kastlunger, R. Stadler, Phys. Rev. B 89, 115412, 2014.

Projektleitung Robert Stadler:
Elektrochemische Interferenz