Abstract
We investigate the magnetoresistance of a side-gated ring structure etched out of single-layer graphene. We observe Aharonov–Bohm oscillations with about 5% visibility. We are able to change the relative phases of the wave functions in the interfering paths and induce phase jumps of π in the Aharonov–Bohm oscillations by changing the voltage applied to the side gate or the back gate. The observed data can be interpreted within existing models for 'dirty metals'.