▎ 摘　　要

We use the charged tip of a low-temperature scanning probe microscope to perturb the transport through a graphene nanoconstriction. Maps of the conductance as a function of tip position display concentric halos and, by following the expansion of the halos with back-gate voltage, we are able to identify an elongated domain over the nanoconstriction where they originate. Amplitude modulations of the transmission resonances are correlated with the gradient of the tip-induced potential and we analyze this in terms of modified tunnel coupling between localized states.