  Atomic vacancies have a strong impact in the mechanical, electronic and
magnetic properties of graphene-like materials. By artificially generating
isolated vacancies on a graphite surface and measuring their local density of
states on the atomic scale, we have shown how single vacancies modify the
electronic properties of this graphene-like system. Our scanning tunneling
microscopy experiments, complemented by tight binding calculations, reveal the
presence of a sharp electronic resonance at the Fermi energy around each single
graphite vacancy, which can be associated with the formation of local magnetic
moments and implies a dramatic reduction of the charge carriers' mobility.
While vacancies in single layer graphene naturally lead to magnetic couplings
of arbitrary sign, our results show the possibility of inducing a macroscopic
ferrimagnetic state in multilayered graphene samples just by randomly removing
single C atoms.
