Evolution of shot noise in suspended lithographic gold break junctions with bias and temperature

Shot noise is a powerful tool to probe correlations and microscopic transport details that conductance measurements alone cannot reveal. Even in atomic-scale Au devices that are well described by Landauer-Büttiker physics, complications remain such as local heating and electron-phonon interactions. We report systematic rf measurements of shot noise in individual atomic-scale gold break junctions at multiple temperatures, with most bias voltages well above the energy of the Au optical phonon mode. Motivated by the previous experimental evidence that electron-phonon interactions can modify Fano factors and result in kinked features in bias dependence of shot noise, we find that the temperature dependence of shot noise from 4.2 to 100 K is minimal. Enhanced Fano factors near [Formula: see text] and features beyond simply linear bias dependence of shot noise near the [Formula: see text] plateau are observed. Both are believed to have non-interacting origins and the latter likely results from slightly bias-dependent transmittance of the dominant quantum channel.