Intrinsic superconducting diode effect and nonreciprocal superconductivity in rhombohedral graphene multilayers

Recent experiments found superconductivity in a four-layer graphene stack where electrons pair chirally in a single momentum-space valley. This spin- and valley-polarized pairing challenges conventional theory and suggests new superconducting orders. Here, the authors present a microscopic explanation for the emergence of such pairing. They show that the same broken symmetries produce an intrinsic superconducting diode effect with direction-dependent critical current. This nonreciprocity is inherent to the graphene stack, requiring no magnetic field. It offers a new platform for field-free, nonreciprocal superconducting transport.