Family of magnetic field-boosted superconductors in rhombohedral graphene

Abstract In some unconventional superconductors, time-reversal symmetry can be broken apart from the gauge symmetry 1 , resulting in superconductivity that can be enhanced or induced by magnetic fields 2 . However, field-enhanced superconductors are more vulnerable to impurities than their Bardeen–Cooper–Schrieffer counterparts 3 . Crystalline rhombohedral multilayer graphene is a promising platform to explore them because of its superior material quality and gate-tunable strong correlation effects 4,5 . Here we report transport measurements of rhombohedral tetralayer and pentalayer graphene, demonstrating a spectrum of clean-limit superconductivities. We found three different types of field-enhanced and field-induced superconductivities in the pentalayer. They are all robust against an in-plane field up to 8.5 T, exceeding the Pauli limit by tens of times. Compared with Bernal bilayer graphene showing only in-plane field-enhancement 6 , pentalayer graphene features superconductors enhanced by out-of-plane as well as in-plane fields. They also reside at much lower gate electric fields owing to the intrinsically flatter band dispersion—facilitating their study and further engineering. Moreover, we observed that proximitized spin–orbit coupling generates multiple new superconductors without introducing additional disorder effects. Our work establishes a new family of magnetic field-boosted superconductors in rhombohedral graphene. Using the high accessibility with moderate gate voltages, this will pave the way for realizing non-Abelian quasiparticles through interfacial engineering 7 in the extreme clean limit, in that proximitized spin–orbit coupling leads to topological states 8 and maintains the ultrahigh quality of crystalline graphene.