Field-Free Topological Edge States of One-Dimensional Rhombohedral Graphene (Part II)

In graphene, strain can generate effective gauge and scalar potentials that mimic electromagnetic potentials. Using scanning tunneling microscopy and spectroscopy (STM/STS), we reveal that in a quasi-one-dimensional rhombohedral graphene system, tensile strain can introduce large pseudoscalar potential. This pseudoscalar potential in the non-Dirac rhombohedral graphene induces flat bands and opens a substantial band gap at zero external displacement field. The gap opening by tensile strain enables the emergence of field-free topological edge states at the ABA–ABC junction. In contrast, in unstrained domains containing a shear-type domain wall, an external displacement field is required to open a bulk gap and drive the topological transition. In this talk, we will present these topological edge states and compare their manifestations in strained and unstrained systems.