Fig. 3: Nontrivial topological properties controlled by the superlattice’s lattice constant and anisotropy.
From: Synergistic correlated states and nontrivial topology in coupled graphene-insulator heterostructures
a, b The distribution of Berry curvature ΩB in the r = 3 superlattice’s Brillouin zone (BZ) of the lowest valence band (VB) and conduction band (CB) in valley K for Ls = 50 and 600 Å, respectively. Their corresponding valley Chern number Cv is also given at the top of each panel. c, d The non-interacting band structure of the r = 3 superlattice with Ls = 50 and 600 Å. The green and orange circles in (a) and (b) indicate spots in the BZ with highly concentrated Berry curvatures, which cause the topological transitions. These spots are generated by band inversion points circled in (c) and (d) using the same colors as in (a) and (b). e Color map of Fermi velocity in the x-direction vx of the valence band for ϵr = 3. The color coding indicates vx/vF. Here we vary Lx from 50 to 600 Å and anisotropy parameter r from 1 to 6. The white dashed line, i.e., the “magic lines”, mark the position in parameter space where vx vanishes.
