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

TL;DR

This study provides the first direct imaging of topological edge states at a bilayer graphene domain wall, revealing their spatial distribution and robustness under high magnetic fields.

Contribution

It is the first to directly visualize topological edge states in bilayer graphene domain walls using scanning tunneling microscopy, combining experimental imaging with theoretical analysis.

Findings

Topological edge states are mainly located at the domain wall edges.

The edge states are robust under high magnetic fields.

The imaging matches well with theoretical predictions.

Abstract

The AB-BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Here we show, for the first time, direct imaging of its topological edge states by using scanning tunneling 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.