Manipulation of magnetism and electronic structure of graphene nanoribbons via porphyrin serration

We use first-principles calculations to systematically investigate the structural, magnetic, and electronic properties of porphyrin-serrated zigzag graphene nanoribbons with 3d transition metal atoms (M = Sc–Zn). Our results reveal that the magnetic ground state and band dispersion near the Fermi level are predominantly governed by the d-electron configuration of the metal centers, whereas the ribbon dimensionality (both width and length) offers an additional degree of freedom for tuning the bandgap and magnetic order. For V-centered systems, the switching between ferromagnetic and antiferromagnetic ground states is fundamentally determined by the electronic structure of the exchange pathway bridging adjacent V centers. In contrast, Mn-, Fe-, and Co-centered nanoribbons exhibit distinct responses to structural modifications. These findings demonstrate that rational selection of the metal center, in combination with dimensional engineering, enables programmable design and precise control over the magnetoelectric properties of these systems.