Gate-Defined Graphene Quantum Point Contact in the Quantum Hall Regime

TL;DR

This paper studies transport properties of a gate-defined graphene quantum point contact in the quantum Hall regime, revealing an unexpected conductance plateau likely caused by chaotic edge channel mixing.

Contribution

It introduces a novel split-gate geometry for graphene quantum point contacts and reports the observation of an unexpected conductance plateau at 0.5 h/e^2.

Findings

Observation of an additional 0.5 h/e^2 plateau in conductance.

Chaotic mixing of edge channels proposed as the cause.

Control of edge states via split-gate geometry.

Abstract

We investigate transport in a gate-defined graphene quantum point contact in the quantum Hall regime. Edge states confined to the interface of p and n regions in the graphene sheet are controllably brought together from opposite sides of the sample and allowed to mix in this split-gate geometry. Among the expected quantum Hall features, an unexpected additional plateau at 0.5 h/e^2 is observed. We propose that chaotic mixing of edge channels gives rise to the extra plateau.