Manipulating quantum Hall edge channels in graphene through Scanning Gate Microscopy

TL;DR

This paper demonstrates precise control and manipulation of quantum Hall edge channels in graphene using a scanning gate microscope, enabling the creation of novel junctions and insights into backscattering phenomena.

Contribution

It introduces a new method to manipulate edge channels in graphene with nanometer precision, revealing phenomena not observed with traditional gating techniques.

Findings

Controlled backscattering of edge channels demonstrated.

Ability to separate co-propagating edge channels.

Creation of novel charge density junctions.

Abstract

We show evidence of the backscattering of quantum Hall edge channels in a narrow graphene Hall bar, induced by the gating effect of the conducting tip of a Scanning Gate Microscope, which we can position with nanometer precision. We show full control over the edge channels and are able, due to the spatial variation of the tip potential, to separate co-propagating edge channels in the Hall bar, creating junctions between regions of different charge carrier density, that have not been observed in devices based on top- or split-gates. The solution of the corresponding quantum scattering problem is presented to substantiate these results, and possible follow-up experiments are discussed.