Correlated and topological states in twisted graphene multilayers

Twisted van der Waals heterostructures have recently emerged as versatile platforms for investigating strongly correlated and/or topological states of matter. The key advantage of these systems lies in the ability to dynamically tune the width and spectral isolation of their flat bands, the Coulomb interaction strength, and the band topology using a combination of tuning knobs including twist angle, doping, displacement field, magnetic field, and pressure. Here, we report electrical transport measurements of twisted monolayer-bilayer graphene (tMBG) and twisted double bilayer graphene (tDBG) over a small range of twist angles around 1°. We identify a variety of tunable correlated states, including those with various types of magnetic ordering driven by either electron spin or orbital motion. In tMBG, the intrinsic band topology additionally leads to the emergence of tunable Chern insulator states. Our results highlight the wide tunability of the correlated and topological states in twisted graphene multilayer heterostructures.