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arXiv · 1007.4271

Current noise in molecular junctions: effects of the electron-phonon interaction

Federica Haupt·Tomas Novotny·Wolfgang Belzig
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Abstract

We study inelastic effects on the electronic current noise in molecular junctions, due to the coupling between transport electrons and vibrational degrees of freedom. Using a full counting statistics approach based on the generalized Keldysh Green's function technique, we calculate in an unified manner both the mean current and the zero-frequency current noise. For multilevel junctions with weak electron-phonon coupling, we give analytical formulas for the lowest order inelastic corrections to the noise in terms of universal temperature- and voltage-dependent functions and junction-dependent prefactors, which can be evaluated microscopically, e.g. with ab-initio methodologies. We identify distinct terms corresponding to the mean-field contribution to noise and to the vertex corrections, and we show that the latter contribute substantially to the inelastic noise. Finally, we illustrate our results by a simple model of two electronic levels which are mutually coupled by the electron-phonon interaction and show that the inelastic noise spectroscopy is a sensitive diagnostic tool.

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Federica Haupt, Tomas Novotny, Wolfgang Belzig. 2010-10-26. Current noise in molecular junctions: effects of the electron-phonon interaction. https://doi.org/10.1103/physrevb.82.165441

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