The issue of whether local magnetic moments can be formed by introducing
adatoms into graphene is of intense research interest because it opens the
window to fundamental studies of magnetism in graphene, as well as of its
potential spintronics applications. To investigate this question we measure, by
exploiting the well-established weak localization physics, the phase coherence
length L_phi in dilute fluorinated graphene. L_phi reveals an unusual
saturation below ~ 10 K, which cannot be explained by non-magnetic origins. The
corresponding phase breaking rate increases with decreasing carrier density and
increases with increasing fluorine density. These results provide strong
evidence for spin-flip scattering and points to the existence of adatom-induced
local magnetic moment in fluorinated graphene. Our results will stimulate
further investigations of magnetism and spintronics applications in
adatom-engineered graphene.Comment: 9 pages, 4 figures, and supplementary materials; Phys. Rev. Lett. in
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