Atomic-level precision creation and manipulation of interfacial Se chemisorbates in graphene/WSe₂ heterostructures

It has long been an ultimate goal to introduce chemical doping at the atomic level to precisely tune properties of materials. Two-dimensional materials have a natural advantage due to their high surface to volume ratio, but achieving this goal experimentally remains a huge challenge. Here, we demonstrate the ability to introduce chemical doping in graphene with atomic-level precision by controlling chemical adsorption of individual Se atoms, which are extracted from the WSe₂ that is underneath, at the interface of the graphene/WSe₂ heterostructures. Our scanning tunneling microscopy (STM) measurements, combined with first-principles calculations, reveal that individual Se atoms can chemisorb on three possible positions in graphene, which generate distinct pseudospin-mediated atomic-scale vortices in graphene. Furthermore, the chemisorbed positions of individual Se atoms can be manipulated by the STM tip, which enables us to achieve atomic-scale control of quantum interference of the pseudospin-mediated vortices in graphene. This result offers the promise of controlling properties of materials with atomic-level precision through chemical doping.