  We critically discuss the stability of edge states and edge magnetism in
zigzag edge graphene nanoribbons (ZGNRs). We point out that magnetic edge
states might not exist in real systems, and show that there are at least three
very natural mechanisms - edge reconstruction, edge passivation, and edge
closure - which dramatically reduce the effect of edge states in ZGNRs or even
totally eliminate them. Even if systems with magnetic edge states could be
made, the intrinsic magnetism would not be stable at room temperature. Charge
doping and the presence of edge defects further destabilize the intrinsic
magnetism of such systems.
