Magneto-transport through graphene nano-ribbons

TL;DR

This paper studies how magnetic fields affect electrical conductance in graphene nano-ribbons, revealing strong localization effects and challenging the idea of a true band gap in these materials.

Contribution

It provides experimental evidence of magneto-transport behavior in graphene nano-ribbons and interprets the results in terms of disorder-induced localization effects.

Findings

Magnetic field increases conductance at a few Tesla

Charging and hopping energy scales decrease with magnetic field

Insulating state is due to disorder, not a true band gap

Abstract

We investigate magneto-transport through graphene nano-ribbons as a function of gate and bias voltage, and temperature. We find that a magnetic field systematically leads to an increase of the conductance on a scale of a few tesla. This phenomenon is accompanied by a decrease in the energy scales associated to charging effects, and to hopping processes probed by temperature-dependent measurements. All the observations can be interpreted consistently in terms of strong-localization effects caused by the large disorder present, and exclude that the insulating state observed in nano-ribbons can be explained solely in terms of a true gap between valence and conduction band.