Pseudospin-mediated Atomic-scale Vortices and Their Quantum Interferences in Monolayer Graphene

Abstract

Vortex is a universal and significant phenomenon that has been known for centuries. However, creating vortices to the atomic limit has remained elusive because that the characteristic length to support a vortex is usually much larger than the atomic scale. Very recently, it was demonstrated that intervalley scattering induced by the single carbon defect of graphene leads to phase winding over a closed path surrounding the defect. Motivated by this, we demonstrate, in this Letter, that the single carbon defects at A and B sublattices of graphene can be regarded as pseudospin-mediated atomic-scale vortices with angular momenta l = +2 and -2, respectively. The quantum interferences measurements of the interacting vortices indicate that the vortices cancel each other, resulting in zero total angular momentum, in the |A| = |B| case, and they show aggregate chirality and angular momenta similar to a single vortex of the majority in the |A| not equal to |B| case, where |A| (|B|) is the number of vortices with angular momenta l = +2 (l = -2).