Intrinsic i‐Wave Altermagnetism in 2D Graphene Superlattices

Altermagnets feature unconventional magnetism due to their momentum‐dependent spin splitting purely driven by magnetic order, for which a variety of transition‐metal‐based ‐wave altermagnets have been proposed. However, carbon‐based altermagnets remain largely unexplored, even though magnetism of graphene nanostructures has been widely demonstrated. Here, through a comprehensive symmetry analysis, we establish a symmetry‐guided design principle for realizing higher‐order ‐wave altermagnetism in graphene antidot superlattices and demonstrate its emergence in both monolayer and bilayer graphene, particularly in the Bernal‐stacked bilayer. By combining atomistic tight binding models and first principles methods, we show the appearance of an interaction‐induced ‐wave altermagnetic splitting, originating from the intrinsic magnetic instability of 2D graphene antidot superlattices. Our work establishes a strategy to engineer ‐wave altermagnetism in a graphene platform, extending the materials landscape beyond conventional ‐wave altermagnets and putting forward a carbon‐based platform for higher‐order altermagnetic spintronics.