Electron-electron interaction and charging effects in graphene quantum dots

TL;DR

This paper investigates charging effects and electron-electron interactions in graphene quantum dots, revealing how these phenomena influence electrostatic potential, Coulomb blockade, and strongly correlated ground states near the neutrality point.

Contribution

It introduces a simple model to analyze charging effects and demonstrates the emergence of strongly correlated states in graphene quantum dots near the neutrality point.

Findings

Charging effects cause Coulomb blockade features when far from neutrality.

Near neutrality, surface states lead to strongly correlated ground states.

Strong correlations modify transport properties with non-equilibrium effects.

Abstract

We analyze charging effects in graphene quantum dots. Using a simple model, we show that, when the Fermi level is far from the neutrality point, charging effects lead to a shift in the electrostatic potential and the dot shows standard Coulomb blockade features. Near the neutrality point, surface states are partially occupied and the Coulomb interaction leads to a strongly correlated ground state which can be approximated by either a Wigner crystal or a Laughlin like wave function. The existence of strong correlations modify the transport properties which show non equilibrium effects, similar to those predicted for tunneling into other strongly correlated systems.