Figure 2. Transport characteristics in bilayer graphene of different angles.

Resistance as a function of gate voltage and magnetic field for different bilayer devices with (d) Bernal stacking, (e) a small rotational mismatch θ=1.5°±0.5° and (f) a mismatch of θ=3.25°±0.75°. The plots above show the according characteristic Shubnikov-de Haas oscillations for the three cases at constant backgate voltages of V_bg=+40 V, +89 V and +60 V, respectively. The blue-striped backdrops highlight (a) the typical Bernal-bilayer sequence with Berry’s phase of 2π (colour changes at every minimum), (b) the monolayer sequence with Berry’s phase of π (colour changes at every maximum) of the main Landau fan and (c) two independent monolayer sequences for different charge carrier densities. The bottom row shows resistance and conductance versus backgate voltage at zero magnetic field for the Bernal stacked bilayer (g), and twisted bilayers of small (h) and larger (i) angle. For the small-angle sample in h, the field effect shows a dip below the expected linear conductance trend (red dotted line) and a shoulder in resistance in the region of the additional Landau fan in e. The blue arrow at the bottom marks the angular range for the predicted different coupling regimes.