Extraordinary magnetoresistance in encapsulated monolayer graphene devices

We report a proof-of-concept study of extraordinary magnetoresistance (EMR) in devices of monolayer graphene encapsulated in hexagonal boron nitride having metallic edge contacts and a central metal shunt. Extremely large EMR values, M R = (R (B) - R 0) / R 0 ∼ 10 5, are achieved in part because R₀ approaches or crosses zero as a function of the gate voltage, exceeding that achieved in high mobility bulk semiconductor devices. We highlight the sensitivity, dR/dB, which in two-terminal measurements is the highest yet reported for EMR devices and in particular exceeds previous results in graphene-based devices by a factor of 20. An asymmetry in the zero-field transport is traced to the presence of pn-junctions at the graphene-metal shunt interface.