Current Noise in Single-Molecule Junctions Induced by Electronic-Vibrational Coupling

TL;DR

This paper investigates how multiple vibrational modes influence current noise in single-molecule junctions, revealing that even weak coupling can cause high noise levels at resonance, aligning with experimental observations.

Contribution

It introduces a generic model analyzing the impact of multiple vibrational modes on current noise, highlighting the significance of electronic-vibrational coupling in molecular junctions.

Findings

High noise levels can occur with weak to moderate coupling at resonance.

Multiple vibrational modes significantly influence current fluctuations.

Results align with experimental data from Secker et al.

Abstract

The influence of multiple vibrational modes on current fluctuations in electron transport through single-molecule junctions is investigated. Our analysis is based on a generic model of a molecular junction, which comprises a single electronic state on the molecular bridge coupled to multiple vibrational modes and fermionic leads, and employs a master equation approach. The results reveal that in molecular junctions with multiple vibrational modes already weak to moderate electronic-vibrational coupling may result in high noise levels, especially at the onset of resonant transport, in accordance with experimental findings of Secker et al..[1] The underlying mechanisms are analyzed in some detail. [1] D. Secker et al., Phys. Rev. Lett. 106, 136807 (2011).