Have Mysterious Topological Valley Currents Been Observed in Graphene Superlattices?

TL;DR

This paper critically examines claims of topological valley currents in graphene superlattices, highlighting inconsistencies and exploring alternative explanations for observed nonlocal transport phenomena.

Contribution

It provides a critical analysis of existing theories on topological valley currents and suggests alternative interpretations and future research directions.

Findings

Identifies inconsistencies in the theoretical explanation of giant nonlocal resistance.

Proposes alternative mechanisms for nonlocal transport in graphene superlattices.

Highlights open questions and directions for future research.

Abstract

We provide a critical discussion concerning the claim of topological valley currents, driven by a global Berry curvature and valley Hall effect proposed in recent literature. After pointing out a major inconsistency of the theoretical scenario proposed to interpret giant nonlocal resistance, we discuss various possible alternative explanations and open directions of research to solve the mystery of nonlocal transport in graphene superlattices.