Structural Determination of Multilayer Graphene via Atomic Moir\'{e} Interferometry

TL;DR

This paper investigates multilayer graphene's moiré patterns caused by layer misalignments and strain, demonstrating how these patterns can be used to determine interlayer strain through atomic moiré interferometry.

Contribution

It introduces a model for three-layer moiré patterns in multilayer graphene and shows how these patterns can be used to measure relative lattice strain.

Findings

Double-moiré patterns observed in multilayer graphene.

Moiré patterns are sensitive to interlayer strain.

Model enables strain measurement via atomic moiré interferometry.

Abstract

Rotational misalignment of two stacked honeycomb lattices produces a moir\'e pattern that is observable in scanning tunneling microscopy as a small modulation of the apparent surface height. This is known from experiments on highly-oriented pyrolytic graphite. Here, we observe the combined effect of three-layer moir\'e patterns in multilayer graphene grown on SiC ($000\bar{1}$). Small-angle rotations between the first and third layer are shown to produce a "double-moir\'e" pattern, resulting from the interference of moir\'e patterns from the first three layers. These patterns are strongly affected by relative lattice strain between the layers. We model the moir\'e patterns as a beat-period of the mismatched reciprocal lattice vectors and show how these patterns can be used to determine the relative strain between lattices, in analogy to strain measurement by optical moir\'e interferometry.