Year: 2005
Type: article
Abstract: It is demonstrated that non-equilibrium vibrational effects are enhanced in molecular devices for which the effective potential for vibrations is sensitive to the charge state of the device. We calculate the electron tunnelling current through a molecule accounting for the two simplest qualitative effects of the charging on the nuclear potential for vibrational motion: a shift (change in the equilibrium position) and a distortion (change in the vibrational frequency). The distortion has two important effects: firstly, it breaks the symmetry between the excitation spectra of the two charge states. This gives rise to new transport effects which map out changes in the current-induced non-equilibrium vibrational distribution with increasing bias voltage. Secondly, the distortion modifies the Franck–Condon factors for electron tunnelling. Together with the spectral asymmetry this gives rise to pronounced nuclear wavefunction interference effects on the electron transport. For instance nuclear-parity forbidden transitions lead to differential conductance anti-resonances , which are stronger than those due to allowed transitions. For special distortion and shift combinations a coherent suppression of transport beyond a bias voltage threshold is possible.
Source: New Journal of Physics
Authors: Maarten R Wegewijs, Katja C Nowack
Institution: RWTH Aachen University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,610
OpenAlex ID: W2118511573