By decorating single-layer graphene with disordered noble metal (Ag, Au, and Pt) clusters, we investigated experimentally the influence of strong random scatterings on graphene transport and electron-localization phenomena. As evidenced by micro-Raman scattering, there is a strong interction between the metal clusters and graphene. We found that such a strong interaction was the consequence of plasma-assisted decoration of the graphene by the metal clusters. A large negative magnetoresistance (MR) effect (up to 80% at 12 T) was observed and fitted using different models. The structure, size, and area density of metal clusters were characterized by scanning tunneling microscopy and transmission electron microscopy. The samples with a high concentration of scattering centers behaved as insulators at low temperatures and showed strong localization (SL) effects. Their temperature-dependent conductance was in accordance with the two-dimensional variable-range hopping (VRH) mechanism. The localization lengths and density of states were estimated and discussed.

• Received 26 February 2011

DOI:https://doi.org/10.1103/PhysRevB.84.045431