Competing magnetic states on the surface of multilayer ABC-stacked graphene

We study interaction-mediated magnetism on the surface of ABC-multilayer graphene driven by its zero-energy topological flat bands. Using the random-phase approximation, we treat onsite Hubbard repulsion and find multiple competing magnetic states, due to both intra- and intervalley scattering, with the latter causing an enlarged magnetic unit cell. At half-filling and when the Hubbard repulsion is weak, we observe two different ferromagnetic orders. Once the Hubbard repulsion becomes more realistic, new ferrimagnetic orders arise with distinct incommensurate intra- or intervalley scattering vectors depending on interaction strength and doping, leading to a multitude of competing magnetic states. Published by the American Physical Society 2024