Magnetotransport through graphene nanoribbons at high magnetic fields

TL;DR

This study explores the magnetoresistance behavior of graphene nanoribbons under high magnetic fields, revealing quantum Hall effects, oscillations, and potential insulating states influenced by disorder and carrier density.

Contribution

It provides combined experimental and simulation insights into how disorder and carrier density affect magnetotransport in graphene nanoribbons at high magnetic fields.

Findings

Observation of Shubnikov-de Haas oscillations and quantum Hall effect at high densities.

Disappearance of oscillations and positive magnetoresistance at low densities.

Edge disorder and bulk impurities significantly influence transport properties.

Abstract

We have investigated the magnetoresistance of lithographically prepared single-layer graphene nanoribbons in pulsed, perpendicular magnetic fields up to 60 T and performed corresponding transport simulations using a tight-binding model and several types of disorder. In experiment, at high carrier densities we observe Shubnikov-de Haas oscillations and the quantum Hall effect, while at low densities the oscillations disappear and an initially negative magnetoresistance becomes strongly positive at high magnetic fields. The strong resistance increase at very high fields and low carrier densities is tentatively ascribed to a field-induced insulating state in the bulk graphene leads. Comparing numerical results and experiment, we demonstrate that at least edge disorder and bulk short-range impurities are important in our samples.