2005/07/30 by Jens Koch, Felix von Oppen
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.72.113308
published as Phys. Rev. B 72, 113308 (2005) · 4+ pages, 3 figures; accepted for publication in Phys. Rev. B. (Brief Reports)
arxiv created 2005/07/30 · arxiv updated 2009/12/01
As a step towards a more realistic modeling of vibrations in single-molecule devices, we investigate the effects of charge-dependent vibrational frequencies and anharmonic potentials on electronic transport. For weak phonon relaxation, we find that in both cases vibrational steps split into a multitude of substeps. This effectively leads to a bias-dependent broadening of vibrational features in current-voltage and conductance characteristics, which provides a fingerprint of nonequilibrium vibrations whenever other broadening mechanisms are secondary. In the case of an asymmetric molecule-lead coupling, we observe that frequency differences can also cause negative differential conductance.