Fig. 4: Fractional QHE in proximity-gated devices.
From: Proximity screening greatly enhances electronic quality of graphene
a, ρxy and ρxx at 12 T and 50 mK (red and blue curves; left and right axes, respectively). Data are plotted as a function of proximity gate voltage, as an accurate conversion to the carrier density was unfeasible due to the 2.5-dimensional QHE in the graphite gate36 and negative quantum capacitance31. ρxy is plotted in terms of ν = (h/e2)/ρxy. Horizontal lines mark expected positions of fractional plateaux. Arrows indicate the corresponding ρxx minima. b, Arrhenius plots for resistance minima (normalized by values at 2 K) at ν = 2/3 and 5/3 were used to extract the activation energies. c, Comparison of fractional QHE gaps in proximity-gated device S1 (red symbols) and a remote-gate device (blue symbols with error bars). Blue rectangular symbols are the expected gaps after proximity screening, calculated using the ℓB/2d suppression factor with d = 1 nm and ℓB ≈ 7.5 nm for 12 T.
