Density of states and magnetoconductance of disordered Au point contacts

TL;DR

This study investigates the low-temperature magnetotransport properties of electrochemically fabricated gold nanojunctions, revealing zero bias anomalies linked to reduced local density of states caused by Coulomb interactions in disordered granular metals.

Contribution

It provides the first low-temperature measurements of atomic-scale gold nanojunctions and links zero bias anomalies to Coulomb interactions affecting the local density of states.

Findings

Zero bias anomalies increase as temperature approaches zero.

Magnetoconductance differs from less constrained devices, supporting Coulomb interaction effects.

Reduced local density of states is consistent with observed anomalies.

Abstract

We report the first low temperature magnetotransport measurements on electrochemically fabricated atomic scale gold nanojunctions. As $T \to 0$, the junctions exhibit nonperturbatively large zero bias anomalies (ZBAs) in their differential conductance. We consider several explanations and find that the ZBAs are consistent with a reduced local density of states (LDOS) in the disordered metal. We suggest that this is a result of Coulomb interactions in a granular metal with moderate intergrain coupling. Magnetoconductance of atomic scale junctions also differs significantly from that of less geometrically constrained devices, and supports this explanation.