Electronic transport and quantum Hall effect in bipolar graphene p-n-p junction

TL;DR

This paper reports on the fabrication and characterization of bipolar graphene p-n-p junctions, revealing fractional quantum Hall conductance plateaus influenced by edge state interactions and backscattering, providing insights into disorder effects.

Contribution

It introduces a new fabrication process for patterned graphene nanostructures with local electrostatic gating and studies fractional quantum Hall effects at p-n interfaces.

Findings

Observation of fractional quantum Hall conductance plateaus.

Sensitivity of plateaus to inter-edge backscattering.

Estimation of disorder strength in graphene devices.

Abstract

We have developed a device fabrication process to pattern graphene into nanostructures of arbitrary shape and control their electronic properties using local electrostatic gates. Electronic transport measurements have been used to characterize locally gated bipolar graphene $p$-$n$-$p$ junctions. We observe a series of fractional quantum Hall conductance plateaus at high magnetic fields as the local charge density is varied in the $p$ and $n$ regions. These fractional plateaus, originating from chiral edge states equilibration at the $p$-$n$ interfaces, exhibit sensitivity to inter-edge backscattering which is found to be strong for some of the plateuas and much weaker for other plateaus. We use this effect to explore the role of backscattering and estimate disorder strength in our graphene devices.