Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 3: TR: Fluctuations and Noise

TT 3.6: Talk

Monday, March 22, 2010, 11:30–11:45, H20

Inelastic noise spectroscopy in molecular junctions with multiple electronic states — •Federica Haupt¹, Tomas Novotny², and Wolfgang Belzig¹ — ¹Department of Physics, Konstanz University, Konstanz, Germany — ²Department of Condensed Matter Physics, Charles University, Prague, Czech Republic

Inelastic transport spectroscopy and shot noise measurements are essential investigation tools in the field of molecular electronics. In fact, while the first allows to extract information on the presence and the orientation of a molecule in a junction, the latter can be used to analyze its individual conductance channels. So far noise measurements have been limited to the elastic transport regime, but more information is expected to be provided by inelastic noise spectroscopy.

In this work we investigate the effects due to inelastic phonon scattering on the current noise in molecular junctions with multiple electronic states. This case is particularly interesting because electron-phonon interaction may results in an effective coupling of different electronic states. Using the extended Keldysh-Green's function formalism we derive a general expression for the zero frequency noise in the case of weak electron-phonon coupling. We compare this result to the case in which transport is dominated by a single electronic state. Finally, we apply our theory to an experimentally relevant set-up.