Evidence for Spin-Flip Scattering and Local Moments in Dilute Fluorinated Graphene

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 similar to 10 K, which cannot be explained by nonmagnetic 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 point to the existence of an adatom-induced local magnetic moment in fluorinated graphene. Our results will stimulate further investigations of magnetism and spintronics applications in adatom-engineered graphene.