Local, global, and nonlinear screening in twisted double-layer graphene

Source abstract

Significance Using scanning tunneling microscopy and numerical simulations we demonstrate that a graphene buffer sheet placed underneath an atomically thin layer is an extremely effective method to increase the quality of 2D electron systems without modifying their electronic structure and without compromising the gating capabilities. We show that owing to its remarkable nonlinear screening capability the graphene buffer layer provides better shielding from substrate-induced perturbations than either increasing the distance to the substrate or doubling the carrier density, or even than using a graphene bilayer.