Emergence of Tertiary Dirac Points in Graphene Moir\'e Superlattices

TL;DR

This paper reports the discovery of tertiary Dirac points in graphene/hBN moiré superlattices, revealing new electronic phenomena and potential hidden superstructures under specific doping and magnetic conditions.

Contribution

It introduces the emergence of tertiary Dirac points in graphene moiré superlattices, a novel electronic feature not previously observed in such systems.

Findings

Tertiary Dirac points form in graphene/hBN moiré superlattices.

Additional Landau levels appear under magnetic fields.

Evidence suggests a hidden Kekulé superstructure.

Abstract

The electronic structure of a crystalline solid is largely determined by its lattice structure. Recent advances in van der Waals solids, artificial crystals with controlled stacking of two-dimensional (2D) atomic films, have enabled the creation of materials with novel electronic structures. In particular, stacking graphene on hexagonal boron nitride (hBN) introduces moir\'e superlattice that fundamentally modifies graphene's band structure and gives rise to secondary Dirac points (SDPs). Here we find that the formation of a moir\'e superlattice in graphene on hBN yields new, unexpected consequences: a set of tertiary Dirac points (TDPs) emerge, which give rise to additional sets of Landau levels when the sample is subjected to an external magnetic field. Our observations hint at the formation of a hidden Kekul\'e superstructure on top of the moir\'e superlattice under appropriate carrier doping and magnetic fields.