Direct imaging of topological edge states at a bilayer graphene domain wall

Abstract

The AB–BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Although it has been extensively studied in theory, a direct imaging of its topological edge states is still missing. Here we image the topological edge states at the graphene bilayer domain wall by using scanning tunnelling microscope. The simultaneously obtained atomic-resolution images of the domain wall provide us unprecedented opportunities to measure the spatially varying edge states within it. The one-dimensional conducting channels are observed to be mainly located around the two edges of the domain wall, which is reproduced quite well by our theoretical calculations. Our experiment further demonstrates that the one-dimensional topological states are quite robust even in the presence of high magnetic fields. The result reported here may raise hopes of graphene-based electronics with ultra-low dissipation.

Generating atomically sharp p−n junctions in graphene and testing quantum electron optics on the nanoscale

“…Further inspection of the quasi-bound states trapping in the GQDs can be measured by STS maps, which reflect the spatial distribution of the LDOS (and consequently the spatial distribution of the confined massless Dirac fermions) at the recorded energies [36][37][38] . Fig.…”

Landau quantization of Dirac fermions in graphene and its multilayers

“…Owing to the varied interlayer stacking around the domain walls, the AB-BA and ABA-ABC stacking solitons can be clearly visualized by STM [73,150], as shown in Figs. 15(c) and (d), by STEM [147] or by infrared nanoscopy [151].…”

“…Graphite -a three-dimensional (3D) allotrope of carbon -consists of stacks of graphene layers with Bernal layer-stacking that are weakly coupled by van der Waals forces [43]. The surface monolayer/few-layer graphene may electronically decouple from graphite when the separation between the topmost graphene layers and the graphite is larger than the equilibrium distance of ∼0.34 nm [45,57,72] or when the sheets have a large rotation angle with respect to the substrate after exfoliation [73]. Hence, it is possible to detect the Landau quantization of 2D Dirac fermions for graphene monolayers and multilayers on the surfaces of such 3D systems [74].…”

“…16(a)]. In STM measurements, the electronically decoupled bilayer graphene on graphite exhibited small-period Moiré patterns because of the large rotation angle with respect to the substrate [73]. The ultra-low random potential fluctuations resulting from substrate imperfections allows us to obtain high-quality atomic-resolution STM images of the 1D domain wall, as shown in Fig.…”

Confining and repulsive potentials from effective non-Abelian gauge fields in graphene bilayers

“…Our analysis becomes relevant as several experimental observations have already shown domain walls between regions of different stacking order in graphene bilayers [15][16][17][18][19].…”