Fig. 4.

Transport characterization of graphene–hBN moiré at 1.5 K. (A) Top optical image shows the hBN-encapsulated monolayer graphene heterostructure prior to patterning. Dashed black outlines indicate the borders of the precharacterized graphene and hBN flakes; the hBN flake being the larger of the two. The stack is patterned into two Hall bars (Bottom optical image), one with a doped Si back gate (Left) and the other with a graphite back gate (Right). Each Hall bar has a metal Top gate. (Scale bars: 20 $\mathrm{\mu }$m.) (B) Top—Color map of longitudinal resistivity in the Left-hand Hall bar of (A), as a function of carrier density $n$ and displacement field $D$. Bottom—Line cut of resistance vs. carrier density along $D=0$. The resistance peak at $n=-5.15e12$ cm⁻² indicates full emptying of the graphene–hBN moiré superlattice ($n/n_s=-4$).