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

Federica Haupt, Tomáš Novotný, and Wolfgang Belzig
Phys. Rev. B 82, 165441 – Published 22 October 2010
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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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  • Received 24 July 2010

DOI:https://doi.org/10.1103/PhysRevB.82.165441

©2010 American Physical Society

Authors & Affiliations

Federica Haupt1,*, Tomáš Novotný2,†, and Wolfgang Belzig1,‡

  • 1Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
  • 2Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, CZ-121 16 Praha 2, Czech Republic

  • *federica.haupt@uni-konstanz.de
  • tno@karlov.mff.cuni.cz
  • wolfgang.belzig@uni-konstanz.de

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Issue

Vol. 82, Iss. 16 — 15 October 2010

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