Quantum transport and field-induced insulating states in bilayer graphene pnp junctions.
We perform transport measurements in high quality bilayer graphene pnp junctions with suspended top gates. At a magnetic field B = 0, we demonstrate band gap opening by an applied perpendicular electric field with an On/Off ratio up to 20,000 at 260 mK. Within the band gap, the conductance decreases exponentially by 3 orders of magnitude with increasing electric field and can be accounted for by variable range hopping with a gate-tunable density of states, effective mass, and localization length. At large B, we observe quantum Hall conductance with fractional values, which arise from equilibration of edge states between differentially doped regions, and the presence of an insulating state at filling factor v = 0. Our work underscores the importance of bilayer graphene for both fundamental interest and technological applications.
Jing
Lei
L
Department of Physics, University of California, Riverside, California 92521, USA.
Velasco
Jairo
J
Kratz
Philip
P
Liu
Gang
G
Bao
Wenzhong
W
Bockrath
Marc
M
Lau
Chun Ning
CN