Zero Bias Anomaly (ZBA)

The current-voltage characteristics through a metallic nanoparticle which is well coupled to a metallic lead are measured. It is shown that the I–V curves are сomposed of two contributions. One is a suppression of the tunneling conductivity at the Fermi level, and the second is an oscillating feature which shifts with gate voltage. The results indicate that zero-bias anomaly and Coulomb blockade phenomena coexist in an asymmetric strongly coupled zero-dimensional system.

We have investigated the I–V characteristics of transport through an asymmetrically coupled metallic grain, which is well connected to one of the leads but poorly connected to the other. This is an unusual regime for which properties usually associated with weakly coupled 0D systems (CB staircases) and disordered higher dimensional leads (Altshuler-Aronov ZBA) appear and may be easily separated. It was shown that in our case the CB and ZBA are both relevant and show a different dependence on the strong coupling of the grain to the lead, temperature, gate, and source-drain voltage. We use these features to determine the parameters of the transport (such as the source and drain resistances) which cannot be separated in regular transport measurements.