  We have carried out an ab initio study of the structural, electronic and
magnetic properties of zigzag graphene nanoribbons on Cu(111), Ag(111) and
Au(111). Both, H-free and H-terminated nanoribbons are considered revealing
that the nanoribbons invariably possess edge states when deposited on these
surfaces. In spite of this, they do not exhibit a significant magnetization at
the edge, with the exception of H-terminated nanoribbons on Au(111), whose
zero-temperature magnetic properties are comparable to those of free-standing
nanoribbons. These results are explained by the different hybridization between
the graphene 2p orbitals and those of the substrates and, for some models, by
the sizable charge transfer between the surface and the nanoribbon.
Interestingly, H-free nanoribbons on Au(111) and Ag(111) exhibit two main peaks
in the local density of states around the Fermi energy, which originate from
different states and, thus, do not indicate edge magnetism.
