  The edge reconstruction of zigzag graphene nanoribbons to a stable line of
alternatively fused seven and five membered rings with hydrogen passivation has
been studied within density functional theory with both localized and extended
basis approximations. Reconstruction of both edges results in a nonmagnetic
metallic ground state, whereas the one edge reconstruction stabilizes the
system in a ferromagnetic metallic ground state. The reconstructed edge
suppresses the local spin density of atoms and contributes finite density of
states at Fermi energy. Our study paves a new way to fabricate the metallic
electrodes for semiconducting graphene devices with full control over the
magnetic behavior without any lattice mismatch between leads and the channel.
