Density of states and magnetoconductance of disordered Au point contacts

We report low-temperature magnetotransport measurements on electrochemically fabricated atomic scale gold nanojunctions. As T⃗0, the junctions exhibit nonperturbatively large zero bias anomalies (ZBA’s) in their differential conductance. We consider several explanations and find that the ZBA’s are consistent with a reduced local density of states 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.