Fig. 2

a Temperature-dependent current-voltage characteristics of bilayer graphene. The inset shows the optical micrograph of the bilayer graphene interconnects with gold electrodes. The measurements show that bilayer graphene intrinsic semiconductor property and the introduction of a perpendicular magnetic field could induce high resistance. b Illustrations of bilayer graphene bandgap and Landau level splitting under the application of the magnetic field. The zero-energy state with respect to up-spin electrons and down-spin holes makes an excitation condensation gap due to the attractive Coulomb force between a hole and an electron.c The relative change resistance ΔR = (G _B = Δ4T  − G _B = 0T ) as a function of magnetic field. Inset: The resistance from the inverse of the gradient of the IV curve (Fig. 2b) as a function of the magnetic field at temperature 5, 200, and 340 K