Theory of Landau level mixing in heavily graded graphene p-n junctions

TL;DR

This paper presents a quantum transport model to analyze Landau level mixing in heavily graded graphene p-n junctions, revealing how junction width and disorder influence Landau level separation and mixing suppression.

Contribution

It introduces a novel simulation approach that spatially resolves carrier transport, demonstrating the impact of junction grading on Landau level mixing in graphene.

Findings

Wide p-n junctions suppress mixing of higher Landau levels.

Spatial separation of Landau levels reduces level mixing.

Simulations match experimental observations from literature.

Abstract

We demonstrate the use of a quantum transport model to study heavily graded graphene p-n junctions in the quantum Hall regime. A combination of p-n interface roughness and delta function disorder potential allows us to compare experimental results on different devices from the literature. We find that wide p-n junctions suppress mixing of $n \neq 0$ Landau levels. Our simulations spatially resolve carrier transport in the device, for the first time, revealing separation of higher order Landau levels in strongly graded junctions, which suppresses mixing.