Insulating state in low-disorder graphene nanoribbons

TL;DR

This study investigates quantum transport in hBN-encapsulated graphene nanoribbons, revealing a magnetic-field-induced energy gap increase due to electron interactions, significantly affecting their electronic properties.

Contribution

First demonstration of magnetic-field-dependent energy gap evolution in hBN-encapsulated graphene nanoribbons highlighting electron-electron interactions.

Findings

Transport gap smaller than on SiO2 substrates

Large energy gap induced at around 3 T magnetic field

Energy gap reaches up to 30 meV at 9 T

Abstract

We report on quantum transport measurements on etched graphene nanoribbons encapsulated in hexagonal boron nitride (hBN). At zero magnetic field our devices behave qualitatively very similar to what has been reported for graphene nanoribbons on $\text{SiO}_2$ or hBN, but exhibit a considerable smaller transport gap. At magnetic fields of around $3~$T the transport behavior changes considerably and is dominated by a much larger energy gap induced by electron-electron interactions completely suppressing transport. This energy gap increases with a slope on the order of $3-4~ $meV/T reaching values of up to $ 30~\mathrm{meV} $ at $ 9~ $T.