Altermagnets have no net magnetisation, yet their electronic bands are spin split. Known candidates are mostly transition-metal compounds; carbon-based versions have been elusive, even though magnetism in graphene nanostructures is well established. Cuiju Yu and Jose Lado of QMAT's Correlated Quantum Materials group at Aalto University propose a symmetry-guided design rule for creating altermagnets in graphene antidot superlattices, graphene sheets perforated with a regular pattern of holes.

Using first-principles methods and atomistic tight-binding models, they show that specific monolayer and bilayer superlattices develop an interaction-induced 'i-wave' altermagnetic splitting, arising from a magnetic instability intrinsic to these structures. The work puts forward graphene as a platform for altermagnetic spintronics.

The preprint has not yet been peer reviewed.

Image: QMAT