Thickness-dependent magnetotransport: from multilayer graphene to few-layer graphene

We present a comparative study of magetoresistance (MR) behaviors in few-layer graphene (FLG) and multilayer graphene (MLG) with various thicknesses. A maximum MR as large as 9500% is observed in a ∼23 nm sample @ 2.5 K, with a non-saturating linear characteristic up to 7 T. MR decreases with increasing temperature and is proportional to the average mobility <μ> in ∼23 nm and ∼12 nm thick samples. In a thinner sample with thickness of ∼1.6 nm, the maximum MR value is only 68% @ 7 T @ 280 K, which is two orders of magnitude smaller than those in the thicker samples. We attribute the MR mechanism of the FLG to mobility fluctuations Δμ. Both the above situations follow the classical Parish and Littlewood model. Through comparison we unveil that both changes in the band structure resulting from a different sample thickness and the disorder induced by sample preparation and graphene/substrate interface are responsible for the MR behavior in the thickness variation. Our results indicate that MR tuning can be realized by precise thickness control in multilayer graphene.