Current noise enhancement: channel mixing and possible nonequilibrium phonon backaction in atomic-scale Au junctions

Abstract

We report measurements of the bias dependence of the Fano factor in ensembles of atomic-scale Au junctions at 77 K. Previous measurements of shot noise at room temperature and low biases have found good agreement of the Fano factor with the expectations of the Landauer- Büttiker formalism, while enhanced Fano factors have been observed at biases of hundreds of mV [R. Chen et al., Sci. Rep. 4, 4221 (2014)]. We find even stronger enhancement of shot noise at 77 K with an "excess" Fano factor up to ten times the low bias value. We discuss the observed ensemble Fano factor bias dependence in terms of candidate models. The results are most consistent with either a bias-dependent channel mixing picture or a model incorporating noise enhancement due to current-driven, nonequilibrium phonon populations, though a complete theoretical treatment of the latter in the ensemble average limit is needed.

25 pages, six figures + supporting information; to appear in J. Phys. Condens. Matt

References in corpus (7)

• Electron-vibration interaction in single-molecule junctions: from contact to tunneling regime
• Phonon-assisted current noise in molecular junctions
• Electron-phonon interaction and full counting statistics in molecular junctions
• Charge transfer statistics of a molecular quantum dot with a vibrational degree of freedom
• Nonlinear effects of phonon fluctuations on transport through nanoscale junctions
• Shot noise suppression at room temperature in atomic-scale Au junctions
• Setup for shot noise measurements in carbon nanotubes

Cited by in corpus (2)

• Hierarchical quantum master equation approach to current fluctuations in nonequilibrium charge transport through nanosystems
• Anomalous electronic shot noise in resonant tunneling junctions