Nanomesh-Type Graphene Superlattice on Au(111) Substrate

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Graphene's interaction with crystalline substrates causes periodic atomic structure modulation due to lattice mismatch.
• Convex superlattices are typically observed for graphene on metal surfaces, while concave geometries are rare.

Purpose of the Study:

• To investigate the formation and characteristics of graphene superlattices on Au(111).
• To explore the origin and stability of concave graphene superlattices.
• To assess the potential of the observed nanomesh structure as a nanoscale template.

Main Methods:

• Scanning Tunneling Microscopy (STM) for atomic-scale imaging.
• Density Functional Theory (DFT) simulations to model atomic interactions.
• Molecular Dynamics (MD) simulations to study surface behavior and reconstruction.

Main Results:

• Observation of a concave graphene superlattice (nanomesh) on Au(111), contrasting with prevalent convex forms.
• Confirmation of the nanomesh structure via DFT and MD simulations.
• Evidence suggesting the nanomesh originates from a surface reconstruction of the Au(111) substrate, with mobile gold atoms playing a key role in stabilization.
• Simultaneous observation of both convex and concave superlattices on herringbone reconstructed Au(111), ruling out contrast inversion as the cause.

Conclusions:

• The study reports the first observation of a concave graphene nanomesh superlattice on Au(111).
• The nanomesh is attributed to a unique surface reconstruction of the gold substrate, stabilized by mobile gold atoms.
• This concave graphene structure presents a novel nanoscale template for self-assembly applications.