Renormalization of the Coulomb blockade gap due to extended tunneling in nanoscopic junctions

TL;DR

This paper investigates how finite-range electron-electron interactions and tunneling affect the Coulomb blockade in nanoscopic junctions, revealing a regime where the blockade gap is significantly reduced due to geometric and screening effects.

Contribution

It introduces a model accounting for extended tunneling and finite-range interactions, showing their combined impact on Coulomb blockade phenomena in nanoscale devices.

Findings

Coulomb blockade gap is reduced when interaction range is smaller than tunneling region.

The blockade gap is strongly renormalized by extended contact energy.

A weakly correlated regime emerges with distinct transport properties.

Abstract

In this work we discuss the combined effects of finite-range electron-electron interaction and finite-range tunneling on the transport properties of ultrasmall tunnel junctions. We show that the Coulomb blockade phenomenon is deeply influenced by the interplay between the geometry and the screening properties of the contacts. In particular if the interaction range is smaller than the size of the tunneling region a "weakly correlated" regime emerges in which the Coulomb blockade gap $\D$ is significantly reduced. In this regime $\D$ is not simply given by the conventional charging energy of the junction, since it is strongly renormalized by the energy that electrons need to tunnel over the extended contact.