Speaker
Description
Flat electronic bands enhance electron–electron interactions and provide a platform for correlated quantum phenomena. We present two complementary approaches to engineering flat bands in graphene. In bulk alternating twisted graphene spirals, photon-energy-dependent angle-resolved photoemission spectroscopy reveals in-plane band flattening at discrete out-of-plane “magic momenta.” These momenta agree quantitatively with theory, with both first- and second-order flat bands observed in the 0.9° structure, extending magic-angle physics into three dimensions. In bilayer graphene, dielectric nanopatterning creates an artificial kagome superlattice with an electrostatically tunable periodic potential. Magnetotransport measurements reveal signatures of a sequence of correlated insulating states that are suppressed at elevated temperatures, while continuum-model calculations capture the formation and evolution of narrow minibands. Together, these results establish dimensionality and artificial lattice design as complementary tools for controlling graphene band structures and exploring correlated electronic states.