Fig. 1: The longitudinal conductivity σ_xx recorded on device D1 as a function of total filling ν_tot and displacement field \(\overline{D}/{\varepsilon }_{int}\) for a fixed magnetic field of 19 T and at a temperature of 30 mK.

a Color rendition of the longitudinal conductivity in the (ν_tot, \(\overline{D}/{\varepsilon }_{int}\))-plane. FQH-states related to two-flux composite fermions are marked at the bottom abscissa with colored boxes containing the total filling. Dotted lines highlight the conductivity minima caused by the condensation of the electrons in the top (white) or bottom (yellow) graphene layer into an integer quantum Hall state with filling 1 or 0. The region marked with red dotted line suffers from metal-graphene contact issue. b Line traces of σ_xx as a function of the displacement electric field for fixed ν_tot of 1/3, 2/3, 4/3, 8/5 and 5/3 in panels i through v from left to right. c Line trace of σ_xx as a function of ν_tot for a fixed displacement field of zero. d Same as (c), but for \(\overline{D}/{\varepsilon }_{int}=-23\) mV/nm. e Same as (c), but for \(\overline{D}v/{\varepsilon }_{int}=-35.5\) mV/nm.