Resonant Interlayer Coupling in NbSe<sub>2</sub>-Graphite Epitaxial Moiré Superlattices.

Abstract

Moiré heterostructures, created by stacking 2D materials together with a finite lattice mismatch or rotational twist, represent a new frontier of designer quantum materials. Typically, however, this requires the painstaking manual assembly of heterostructures formed from exfoliated materials. Here, clear spectroscopic signatures of moiré lattice formation in epitaxial heterostructures of monolayer (ML) NbSe₂ grown on graphite substrates are observed. Angle-resolved photoemission measurements and theoretical calculations of the resulting electronic structure reveal moiré replicas of the graphite π states forming pairs of interlocking Dirac cones. Interestingly, these intersect the NbSe₂ Fermi surface at the k$k$ -space locations where NbSe₂'s charge-density wave (CDW) gap is maximal in the bulk. This provides a natural route to understand the lack of CDW enhancement for ML-NbSe₂/graphene as compared to a more than fourfold enhancement for NbSe₂ on insulating support substrates, and opens new prospects for using moiré engineering for controlling the collective states of 2D materials.