MAGNETOTRANSPORT IN CARBON FOILS FABRICATED FROM EXFOLIATED GRAPHITE

The magnetotransport properties of a series of low-density carbon foil s, fabricated from exfoliated graphite, prepared with different densit ies and subjected to different heat treatments, have been investigated . The Hall resistance and the magnetoresistance were measured at low t emperatures (T>0.4 K) in magnetic fields up to B = 8 T. The transport properties showed the main features of weak localization, i.e., a loga rithmic temperature variation of the resistivity and a negative magnet oresistance for B<0.5 T at low temperatures. The negative contribution to the magnetoresistance has been analyzed within the model of Wittma nn and Schmid for weak localization beyond the diffusion limit. The an alysis yields the phase relaxation time tau(phi) of the carrier wave f unction. The structural analysis of the carbon foils shows that the we ak localization must be attributed to the disorder in the stacking seq uence of the graphene planes. [S0163-1829(98)08515-4].