Using carbon chains to mediate magnetic coupling in zigzag graphene nanoribbons

Graphene nanoribbon and atomic carbon chain are allotropes of carbon, attracting tremendous attention from multidisciplinary areas ranging from nano physics to astrophysics. Here, first-principles calculations based on density-functional theory are carried out to study the ferromagnetic coupling in zigzag-edged graphene nanoribbons linked by carbon chains. Compared to the existing methods for ferromagnetic graphene nanoribbons, carbon chain linkage is found to be more effective for larger magnetic exchange energy and also be more flexible in tuning the electronic structure and magnetism.