Fig. 1: Nano-imaging of moiré lattice dynamics in t-hBN.
From: Nanoscale lattice dynamics in hexagonal boron nitride moiré superlattices
a Schematic of near-field imaging of t-hBN sample on a graphite/SiO2/Si substrate. As illustrated by arrows, light scatters off the tip and is sent to a detector. When scanning the tip over the moiré region, we observe a triangular lattice. A schematic of a relaxed superlattice is shown underneath the tip. The possible stacking configurations are drawn above (AA, AB, BA). All experiments are performed with a laser tuned in the vicinity of the transverse optical (TO) phonon frequency. The eigenmode is illustrated on the left, where atoms oscillate orthogonally to the wavevector qTO. b, c Images of the near-field amplitude taken at two selected frequencies for sample 1 (bilayer–monolayer stacking). d, e Images of the near-field phase taken at two selected frequencies for sample 1. f Large-area piezo-force microscopy (PFM) image of sample 2 (monolayer–monolayer stacking). The white dashed rectangle shows the region studied with near-field imaging. The inset shows unbiased DC electrical force microscopy (dc-EFM) imaging. g–i Images of the near-field amplitude taken at three selected frequencies for sample 2 (monolayer–monolayer stacking). j–l Images of the near-field phase taken at three selected frequencies for sample 2.
