Graphene’s superconductivity persists even with strong electrostatic control

Researchers have demonstrated complete suppression of superconductivity in magic-angle twisted bilayer graphene (TBG) through tunable electrostatic screening, achieving variations in critical temperature by more than an order of magnitude. The work challenges existing theories surrounding the unconventional origins of superconductivity in this material, where the maximum of the critical temperature T C roughly coincides with the 1.1° twist angle between graphene layers where the flattened energy bands maximize electron-electron interactions. Previous studies yielded conflicting results; V-shaped differential conductance in tunnelling spectra supported unconventional pairing, while experiments employing graphite gates pointed towards phonon-mediated superconductivity. The gates were separated by thin (6-10 nm) hexagonal boron nitride (hBN) spacers.…