Figure 1: Edges and LLs and graphene structure.
From: Evolution of Landau levels into edge states in graphene
(a) Edge reconstruction in semiconductor-based 2DES. The distances from gates and screening plane are much larger than the magnetic length. Top: spatial variation of LL energy as a function of distance from the edge shows the effect of edge-state reconstruction. Dashed lines mark the boundary between compressible and incompressible strips. Bottom: spatial variation of the reconstructed carrier density close to the edge. (b) Same as in a for graphene and distances from screening planes that are much smaller than the magnetic length. Inset: schematic illustration of graphene sample and screening plane. (c) STM of a graphene flake on a graphite substrate near a zigzag edge measured in a field of 4 T at 4.4 K. Inset: the edge type is determined from atomic-resolution STM at a distance of ~32 nm=2.5 lB from the edge (position 6 ). The dashed line marks a zigzag direction and is parallel to the edge, also marked with a dashed line in the main panel. LL spectra taken at intervals of 0.5 lB (at the positions marked 1–6) and averaged over an area 0.4 × 0.4 nm2 (marked by the white square in the inset for position 6) are shown in Fig. 2. Scale bars: 5 nm (main panel), 500 pm (inset). The rectangles at position 1, 2 and 6 indicate the areas of the topography maps in Fig. 4 and the inset. (d) Graphene edges. The two sublattices in the honeycomb structure are denoted A and B. The zigzag edge termination contains either A- or B-type atoms, whereas the armchair contains both types. (e) Atomic-resolution STM topography measured far from the edge shows the honeycomb structure with a slight intensity asymmetry on the two sublattices. Scale bar: 500 pm. (f) Intensity plot taken along the line in panel e displays an intensity modulation where one of the sublattices, marked A, appears 10% less intense than the other marked B.
