Single-Valley Engineering in Graphene Superlattices

TL;DR

This paper proposes engineering a chiral single-valley metallic phase in graphene superlattices, enabling valley polarization control and potential applications in photonic crystals, advancing valleytronics and topological material research.

Contribution

It introduces a method to create a single-valley metallic phase in graphene via tailored superlattices and explores valley manipulation techniques.

Findings

Realization of a single-valley metallic phase in graphene.

Tunable valley polarization through pseudo-Zeeman fields.

Emergence of Dresselhaus-type valley-orbit coupling.

Abstract

The two inequivalent valleys in graphene preclude the protection against inter-valley scattering offered by an odd-number of Dirac cones characteristic of Z2 topological insulator phases. Here we propose a way to engineer a chiral single-valley metallic phase with quadratic crossover in a honeycomb lattice through tailored \sqrt{3}N *\sqrt{3}N or 3N *3N superlattices. The possibility of tuning valley-polarization via pseudo-Zeeman field and the emergence of Dresselhaus-type valley-orbit coupling are proposed in adatom decorated graphene superlattices. Such valley manipulation mechanisms and metallic phase can also find applications in honeycomb photonic crystals.