heterostructures: Part 2*

Magic-angle twisted bilayer graphene (TBG) hosts a multitude of correlated insulating, superconducting, and topological phases. We show that adding an insulating monolayer of WSe₂ to the TBG stabilizes superconductivity down to angles as small as 0.79°. At angles in this range, both the correlated insulating states and the band gaps between flat and dispersive bands disappear, leading to metallic behavior across the accessible range of electron density. We additionally observe weak antilocalization and the breaking of the fourfold spin-valley symmetry usually observed in TBG, consistent with strong spin-orbit coupling. Further, in-plane and out-of-plane magneto-transport measurements reveal that finite-field correlated phases also persist for twist angles well below the magic angle value. Our results constrain theoretical explanations for the superconductivity and correlated insulators in TBG and emphasize the importance of the dielectric substrates for engineering of the electronic states in moiré systems.