Scanning gate microscopy on a graphene quantum point contact

In this paper, we present scanning gate microscopy (SGM) measurements on a graphene quantum point contact, carried out under ambient conditions. Images obtained in SGM display two-dimensional maps of sample resistance, as a function of the position of a biased AFM tip and the voltage applied to the tip. In our studies, a graphene quantum point contact was fabricated using local anodic oxidation. Performing SGM imaging on the resulting device structure shows that the resistance through the graphene QPC is strongly affected by the electric field of the AFM tip at the position of the QPC.