Magnetic field induced charge redistribution in disordered graphene double quantum dots

TL;DR

This study investigates how magnetic fields influence charge distribution in disordered graphene double quantum dots, revealing increased dot size and charge delocalization at high magnetic fields through experimental and theoretical analysis.

Contribution

It provides new insights into magnetic field effects on charge redistribution in disordered graphene quantum dots using a tight-binding model and experimental transport measurements.

Findings

Charging energy decreases at high magnetic fields

Quantum dot size increases with magnetic field

Charge delocalization occurs due to barrier transparency

Abstract

We have studied the transport properties of a large graphene double quantum dot under the influence of background disorder potential and magnetic field. At low temperatures, the evolution of the charge-stability diagram as a function of B-field is investigated up to 10 Tesla. Our results indicate that the charging energy of quantum dot is reduced, and hence the size of the dot increases, at high magnetic field. We provide an explanation of our results using a tight-binding model, which describes the charge redistribution in a disordered graphene quantum dot via the formation of Landau levels and edge states. Our model suggests that the tunnel barriers separating different electron/hole puddles in a dot become transparent at high B-fields, resulting in the charge delocalization and reduced charging energy observed experimentally.