Giant magnetoresistance in single-layer graphene flakes with a gate-voltage-tunable weak antilocalization

A clear gate-voltage-tunable weak antilocalization and a giant magnetoresistance of similar to 400% are observed at 1.9 K in single-layer graphene with an out-of-plane field. A large magnetoresistance value of 275% is obtained even at room temperature, implying potential applications of graphene in magnetic sensors. Both the weak antilocalization and giant magnetoresistance persists far away from the charge neutrality point, in contrast to previous reports, and both effects originate from charged impurities. Interestingly, the signatures of Shubnikov-de Haas oscillations and the quantum Hall effect are also observed for the same sample.