Fig. 1: Characterization of a large-angle twisted bilayer graphene (LATBG) device.

a Top panel: schematic structure of LATBG device, utilizing thin hBN flakes as dielectrics for bottom graphite and top metal gates, \({V}_{{\mbox{tg}}}\) and \({V}_{{\mbox{bg}}}\) are top and bottom gate voltages; bottom panel: optical image of LATBG Hall bar device. Black line highlights the metallic top gate and electrical contacts. Scale bar is 1 μm. b Longitudinal resistivity as a function of total charge density \({n}_{{\mbox{tot}}}\) for D = 0 V/nm, and D = 0.5 V/nm measured at zero magnetic field. Dashed circles indicate the positions of charge neutrality points of top (t-CNP, black circle) and bottom graphene layers (b-CNP, blue circle) calculated using the electrostatic model (see Supplementary Note 1). Insets schematically show band structure of LATBG under applied D when the Fermi level crosses the CNP of one of the graphene layers; here, the red part of the cone represents hole doping, and blue represents electron doping of graphene. c Longitudinal resistivity at B = 0 T as a function of \({n}_{{\mbox{tot}}}\) and D. Dashed lines indicate expected positions of CNPs. d, e Resistivity as a function of magnetic field B and \({n}_{{\mbox{tot}}}\) for D = 0 V/nm (d) and D = 0.6 V/nm (e). In (d) dashed lines show the expected position of doubled graphene filling factors. In (e) white dashed lines are a guide for the eye of the first three Landau levels and CNP gap boundaries in bottom graphene layer. See the text for the further discussion. Further examples of Landau fan measurements are shown in Supplementary Figs. 2 and 4. The high magnetoresistance observed around \({n}_{{\mbox{tot}}}=0\) can be attributed to the compensated semimetal state, similar to ref. ²⁴, which naturally forms under applied D when one layer is electron-doped and the other is hole-doped. Measurements were performed at 2 K for all panels.