Strain-induced doping and zero line mode at the fold of twisted Bernal-stacked bilayer graphene

Abstract The folding of Bernal-stacked bilayer graphene leads to electronic devices that can be understood as combinations of a twisted double-bilayer graphene and a fold. In magnetotransport experiments contributions of the two different parts can be identified. For the twisted double-bilayer graphene Landau fan diagrams with satellite fans depending on twist angle are observed. The fold gives rise to a local minimum in conductance which does not shift with applied perpendicular magnetic field. Regardless of twist angle the fold favors electron doping attributed to compressive strain at the kink geometry. The curvature of the folded structure provides for a systematic explanation, which is also in agreement with the observed correlation between twist angle and interlayer distance. Finally, the appearance of the topological zero line mode formed at the fold is discussed.