Rickhaus P Liu MH Kurpas M Kurzmann A Lee Y Overweg H Eich M Pisoni R Taniguchi T Watanabe K Richter K Ensslin K Ihn T 2020 When two dimensional crystals are atomically close, their finite thickness becomes relevant. Using transport measurements, we investigate the electrostatics of two graphene layers, twisted by θ = 22° such that the layers are decoupled by the huge momentum mismatch between the K and K' points of the two layers. We observe a splitting of the zero-density lines of the two layers with increasing interlayer energy difference. This splitting is given by the ratio of single-layer quantum capacitance over interlayer capacitance C m and is therefore suited to extract C m. We explain the large observed value of C m by considering the finite dielectric thickness d g of each graphene layer and determine d g ≈ 2.6 Å. In a second experiment, we map out the entire density range with a Fabry-Pérot resonator. We can precisely measure the Fermi wavelength λ in each layer, showing that the layers are decoupled. Our findings are reproduced using tight-binding calculations. application/pdf https://sonar.ch/global/documents/250483 eng info:eu-repo/semantics/altIdentifier/doi/10.1126/sciadv.aay8409 info:eu-repo/semantics/altIdentifier/pmid/32201727 info:eu-repo/semantics/openAccess Science advances. - 2020 The electronic thickness of graphene. http://purl.org/coar/resource_type/c_6501