Low voltage conductance of small tunnel junctions

TL;DR

This paper investigates the nonequilibrium conductance properties of small tunnel junctions with Coulomb interactions, revealing novel effects such as leakage currents within the Coulomb gap and divergent conductance under certain electronic interactions.

Contribution

It introduces a simple model to analyze how Coulomb interactions affect conductance in small tunnel junctions, uncovering effects not previously described.

Findings

Leakage current exists within the Coulomb gap for identical electrodes.

Differential conductance diverges with attractive electron interactions.

Conductance is suppressed with repulsive interactions.

Abstract

A discrete charge transfer in a small tunnel junction where Coulomb interactions are important can excite electron-hole pairs near the Fermi level. We use a simple model to study the associated nonequilibrium properties and found two novel effects: (i) for junctions with electrodes of the same electronic properties, a leakage current exists within the Coulomb gap even when the environmental impedance is infinite; (ii) for junctions with electrodes of different electronic properties, the differential conductance diverges when a net interaction between conduction electrons is attractive, and it is strongly suppressed for a net repulsive interaction.