  We study the spin-wave excitations near the zigzag edge of graphene. It is
rather interesting that we obtain a single branch of relativistic ferromagnetic
magnon due to the presence of the open boundary. Note that magnons in
antiferomagnets appear in pairs, while the single brach magnon in ferromagnets
does not have relativistic dispersion. Thus, the magnon near the zigzag edge of
graphene is a hybrid of both, signaling its intrinsic property as a boundary
excitation that must be embedded in a higher dimensional bulk system.
