The electronic quality of graphene has improved significantly over the past two decades, revealing novel phenomena. However, even state-of-the-art devices exhibit substantial spatial charge fluctuations originating from charged defects inside the encapsulating crystals, limiting their performance. Here, we overcome this issue by assembling devices in which graphene is encapsulated by other graphene layers while remaining electronically decoupled from them via a large twist angle (~10–30°). Doping of the encapsulating graphene layer introduces strong Coulomb screening, maximized by the sub-nanometer distance between the layers, and reduces the inhomogeneity in the adjacent layer to just a few carriers per square micrometre. The enhanced quality manifests in Landau quantization emerging at magnetic fields as low as ~5 milli-Tesla and enables resolution of a small energy gap at the Dirac point. Beyond large-angle graphene encapsulation, similar screening can be achieved using a graphite layer separated from graphene by an ultrathin three-layer hBN spacer. In such devices, we observe quantum oscillations appearing already at 1 mT, carrier inhomogeneity suppressed to 10⁷ cm⁻², and transport mobilities exceeding 6 × 10⁷ cm² V⁻¹ s⁻, surpassing those of state-of-the-art GaAs 2DEGs and establishing graphene devices with screening as the highest-mobility material ever created.

But I will probably also speak about other our recent results, which are not that well fit into the abstract, but maybe interesting for a public.