Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 14: Transport: Nanoelectronics III - Molecular Electronics
TT 14.12: Vortrag
Dienstag, 26. Februar 2008, 12:30–12:45, H 3010
Quantum fluctuations and vibration-assisted transport through single molecule transistors — •Martin Leijnse1,2, Maarten Wegewijs1,2, and Herbert Schoeller1 — 1Institut für Theoretische Physik A, RWTH Aachen, 52056 Aachen, Germany — 2Institut für Festkörper-Forschung - Theorie 3, Forschungszentrum Jülich, 52425 Jülich, Germany
Non-equilibrium transport through a single molecule transistor is studied in the presence of strong coupling to a local vibrational mode. Employing a full fourth order perturbation expansion in the tunneling Hamiltonian, we address the experimentally relevant regime of intermediate tunneling coupling between molecule and electrodes. Using the real-time transport theory we calculate the nonlinear conductance, accounting for the so-called cotunneling contributions, as well as renormalization and broadening effects, induced by charge fluctuations. We find that broadening and in-elastic cotunneling processes are of comparable importance for the lifting of the vibration-induced Franck-Condon blockade. Strikingly, novel transport features connected to this broadening are found below the bias-voltage threshold for in-elastic cotunneling, which have gone unnoticed until now. Relaxation of the vibrational distribution, induced by coupling to an external phonon bath, leads to a uniform reduction of all higher order processes, i.e. broadening and in-elastic effects remain comparable.