  It is shown that apart from well-known factors, like temperature, substrate,
and edge reconstruction effects, also the presence of external contacts is
destructive for the formation of magnetic moments at the edges of graphene
nanoribbons. The edge magnetism gradually decreases when graphene/electrode
interfaces become more and more transparent for electrons. In addition to the
graphene/electrode coupling strength, also the aspect ratio parameter, i.e. a
width/length ratio of the graphene nanoribbon, is crucial for the suppression
of edge magnetism. The present theory uses a tight-binding method, based on the
mean-field Hubbard Hamiltonian for $\pi$ electrons, and the Green's function
technique within the Landauer-B\"uttiker approach.
