Atomic-Scale Imaging of Lattice Relaxation and Topological Flat Bands in Helical Trilayer Graphene
Researchers used atomic-scale imaging (SNOM, AFM) and spectroscopy (LT-STM/STS) to link lattice relaxation to electronic properties in Helical Trilayer Graphene (HTG). They found that strain modifies the moiré structure, leading to isolated flat bands with a honeycomb texture. Crucially, they identified an experimental 'magic angle' of 1.9°, larger than theoretical predictions, confirming a direct microscopic link between atomic structure and narrow electronic states.