Transport through a strongly coupled graphene quantum dot in perpendicular magnetic field

TL;DR

This study investigates transport properties of a strongly coupled graphene quantum dot under perpendicular magnetic fields, revealing Landau level formation and localized states affecting quantum spectra.

Contribution

It provides new insights into magnetic field effects on graphene quantum dots, including Landau level formation and localized state development.

Findings

Observation of Coulomb resonances and diamonds with 4.5 meV charging energy

Evolution of Coulomb resonances indicating 0th Landau level formation

Complex energy spectra due to localized states at high magnetic fields

Abstract

We present transport measurements on a strongly coupled graphene quantum dot in a perpendicular magnetic field. The device consists of an etched single-layer graphene flake with two narrow constrictions separating a 140 nm diameter island from source and drain graphene contacts. Lateral graphene gates are used to electrostatically tune the device. Measurements of Coulomb resonances, including constriction resonances and Coulomb diamonds prove the functionality of the graphene quantum dot with a charging energy of around 4.5 meV. We show the evolution of Coulomb resonances as a function of perpendicular magnetic field, which provides indications of the formation of the graphene specific 0th Landau level. Finally, we demonstrate that the complex pattern superimposing the quantum dot energy spectra is due to the formation of additional localized states with increasing magnetic field.