Magnetoresistance measurements of Graphene at the Charge Neutrality Point

TL;DR

This study investigates the insulating state at the charge neutrality point of graphene under high magnetic fields, revealing it is not spin polarized and providing insights into its bulk and edge conductance properties.

Contribution

It provides the first detailed transport measurements distinguishing bulk and edge conductance in graphene's insulating state at high magnetic fields.

Findings

Conductance vanishes with increasing magnetic field

Insulating state is not spin polarized

Bulk and edge conductance measurements agree

Abstract

We report on transport measurements of the insulating state that forms at the charge neutrality point of graphene in a magnetic field. Using both conventional two-terminal measurements, sensitive to bulk and edge conductance, and Corbino measurements, sensitive only to the bulk conductance, we observed a vanishing conductance with increasing magnetic fields. By examining the resistance changes of this insulating state with varying perpendicular and in-plane fields, we probe the spin-active components of the excitations in total fields of up to 45 Tesla. Our results indicate that \nu=0 quantum Hall state in single layer graphene is not spin polarized.