Spin transport in a graphene normal-superconductor junction in the quantum Hall regime

TL;DR

This paper investigates how coupling graphene in the quantum Hall regime to a superconductor induces spin-filtered charge transport due to unique edge state interactions influenced by a Zeeman field.

Contribution

It reveals a novel spin-filtering mechanism in graphene-superconductor junctions under quantum Hall conditions, highlighting the role of Andreev reflections and Zeeman effects.

Findings

Spin-filtered charge transport occurs at the graphene-superconductor interface.

The effect arises from the interplay of specular and retro Andreev reflections.

Zeeman field creates energy regions with opposite spin propagation at the edges.

Abstract

The quantum Hall regime of graphene has many unusual properties. In particular, the presence of a Zeeman field opens up a region of energy within the zeroth Landau level, where the spin-up and spin-down states localized at a single edge propagate in opposite directions. We show that when these edge states are coupled to an s-wave superconductor, the transport of charge carriers is spin-filtered. This spin-filtering effect can be traced back to the interplay of specular Andreev reflections and Andreev retro-reflections in the presence of a Zeeman field.