  We investigate the effects of randomly distributed atomic defects on the
magnetic properties of graphene nanoribbons with zigzag edges using an extended
mean-field Hubbard model. For a balanced defect distribution among the
sublattices of the honeycomb lattice in the bulk region of the ribbon, the
ground state antiferromagnetism of the edge states remains unaffected. By
analyzing the excitation spectrum, we show that while the antiferromagnetic
ground state is susceptible to single spin flip excitations from edge states to
magnetic defect states at low defect concentrations, it's overall stability is
enhanced with respect to the ferromagnetic phase.
