Quantum transport in double-gated graphene devices

Double-gated graphene devices provide an important platform for understanding electrical and optical properties of graphene. Here we present transport measurements of single layer, bilayer and trilayer graphene devices with suspended top gates. In zero magnetic fields, we observe formation of pnp junctions with tunable polarity and charge densities, as well as a tunable band gap in bilayer graphene and a tunable band overlap in trilayer graphene. In high magnetic fields, the devices’ conductance are quantized at integer and fractional values of conductance quantum, and the data are in good agreement with a model based on edge state equilibration at pn interfaces.

► Formation of grahene pnp junctions.
► Demonstration of edge state equilibration in trilayer in single-, bi- and tri-layer graphen devices.
► Observation of band gap opening in dual-gated bilayer graphene.
► Observation of band overlap in dual-gated trilayer graphene.