Inter-Edge Backscattering in Buried Split-Gate-Defined Graphene Quantum Point Contacts

TL;DR

This paper introduces a buried split-gate architecture in monolayer graphene that enables precise control of edge states and inter-edge scattering, advancing the study of quantum transport phenomena in quantum Hall regimes.

Contribution

It presents a novel buried split-gate design in graphene for controlling quantum edge trajectories and fractional resistances, with successful experimental and theoretical modeling.

Findings

Observation of fractional quantum resistances due to inter-edge scattering

Successful numerical and Landauer-Buettiker modeling of transport

Graphene's top-layer position facilitates scanning probe investigations

Abstract

Quantum Hall effects offer a formidable playground for the investigation of quantum transport phenomena. Edge modes can be detected, branched, and mixed by designing a suitable potential landscape in a two-dimensional conducting system subject to a strong magnetic field. In the present work, we demonstrate a buried split-gate architecture and use it to control electron conduction in large-scale single-crystal monolayer graphene grown by chemical vapor deposition. The control of the edge trajectories is demonstrated by the observation of various fractional quantum resistances, as a result of a controllable inter-edge scattering. Experimental data are successfully modeled both numerically and within the Landauer-Buettiker formalism. Our architecture is particularly promising and unique in view of the investigation of quantum transport via scanning probe microscopy, since graphene constitutes the topmost layer of the device. For this reason, it can be approached and perturbed by a scanning probe down to the limit of mechanical contact.