Cotunneling transport in ultra-narrow gold nanowire bundles

We investigate the charge transport in close-packed ultra-narrow (1.5 nm diameter) gold nanowires stabilized by oleylamine ligands. We give evidence of charging effects in the weakly coupled one-dimensional (1D) nanowires, monitored by the temperature and the bias voltage. At low temperature, in the Coulomb blockade regime, the current flow reveals an original cooperative multi-hopping process between 1D-segments of Au-NWs, minimising the charging energy cost. Above the Coulomb blockade threshold voltage and at high temperature, the charge transport evolves into a sequential tunneling regime between the nearest-nanowires. Our analysis shows that the effective length of the Au-NWs inside the bundle is similar to the 1D localisation length of the electronic wave function (of the order of 120 nm ± 20 nm), but almost two orders of magnitude larger than the diameter of the nanowire. This result confirms the high structural quality of the Au-NW segments.