Superconductivity from dual-surface carriers in rhombohedral graphene

Rhombohedral graphene at charge neutrality hosts an unusual low-energy electronic wavefunction that is predominantly localized at its top and bottom layers and has negligible presence in the bulk. Increasing the number of graphene layers amplifies the density of states near charge neutrality and thereby enhances the susceptibility to symmetry-breaking phases. Here we report superconductivity in rhombohedral graphene arising from this charge-delocalized semimetallic normal state, which is characterized by coexisting valence- and conduction-band Fermi pockets split over opposite crystal surfaces. In octalayer graphene, the superconductivity appears in five apparently distinct regions of the phase diagram for each sign of an external electric displacement field. In a moiré superlattice sample where heptalayer graphene is aligned on one side to hexagonal boron nitride, two regions of superconductivity emerge from a single sharp resistive feature. At higher displacement field, the same resistive feature additionally induces an anomalous Hall state quantized at h/e2 when the doping is close to one electron per moiré unit cell. Our findings highlight the various superconducting regimes in multilayer graphene and create opportunities for coupling to nearby topological states. Two different types of medium-thickness rhombohedral graphene are shown to exhibit multiple superconducting states. These states arise from wavefunctions that are localized mainly on their two outer layers.