Imaging of Submicroampere Currents in Bilayer Graphene Using a Scanning Diamond Magnetometer
Marius L. Palm, William S. Huxter, Pol Welter, Stefan Ernst, Patrick Scheidegger, S. Diesch, Kai Chang, Peter Rickhaus, Takashi Taniguchi, Kenji Watanabe, K. Ensslin, Christian L. Degen
Abstract
Current imaging via scanning diamond magnetometry is a valuable tool in the study of transport phenomena, due to its applicability over a wide temperature range, but its sensitivity for resolving subtle features and small currents has remained limited. By implementing ac measurement protocols and phase-unwrapping schemes, the authors detect currents below 1 \textmu{}A in bilayer graphene, and resolve minute variations on top of background signals. They also observe current-density variations due to a varying background potential, and discuss measurement-induced back-action and how to avoid it. These advances establish scanning diamond magnetometry as an excellent option for current imaging.