Magnetotransport in carbon foils fabricated from exfoliated graphite

Abstract

The magnetotransport properties of a series of low-density carbon foils, fabricated from exfoliated graphite, prepared with different densities and subjected to different heat treatments, have been investigated. The Hall resistance and the magnetoresistance were measured at low temperatures $(T>\mathrm{}0.4\mathrm{}\mathrm{K})$ in magnetic fields up to $B=8\mathrm{}\mathrm{T}.$ The transport properties showed the main features of weak localization, i.e., a logarithmic temperature variation of the resistivity and a negative magnetoresistance for $B<\mathrm{}0.5\mathrm{}\mathrm{T}$ at low temperatures. The negative contribution to the magnetoresistance has been analyzed within the model of Wittmann and Schmid for weak localization beyond the diffusion limit. The analysis yields the phase relaxation time ${\tau }_{\phi }$ of the carrier wave function. The structural analysis of the carbon foils shows that the weak localization must be attributed to the disorder in the stacking sequence of the graphene planes.