Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 99: Poster Session: Transport
TT 99.7: Poster
Donnerstag, 15. März 2018, 15:00–19:00, Poster B
Bias-dependent forces in single-molecule junctions — •Susanne Leitherer1, Jonathan Brand2, Nick P. Rübner1, Nicolas Neel2, Jörg Kröger2, and Mads Brandbyge1 — 1Department of Micro- and Nanotechnology, Technical University of Denmark — 2Institut für Physik, Technische Universität Ilmenau
We study the forces on single-molecule junctions formed by C60-terminated Cu tips and C60 molecules adsorbed on Cu(111) employing first principles electronic structure and transport calculations based on density functional theory combined with non-equilibrium Greens functions (DFT-NEGF). The C60-C60 bond force evaluated at different distances and voltages shows an asymmetric dependence on the bias polarity. This asymmetry can be related to bias-dependent electrostatic forces between the charge densities localized at the molecules, and also indicates the effect of current-induced forces. We discuss various ways to rationalize these forces in terms of transmission eigenchannels, charge redistribution, overlap populations and bond-currents. Our simulations support the results of scanning tunneling microscopy studies on the junctions using bias-dependent force spectroscopy, which cannot be explained without accounting for the non-equilibrium forces in single-molecule junctions.