Magnetotransport in mesoscopic carbon networks in the vicinity of metal–insulator transition

Abstract The magnetoresistance (MR) in the magnetic fields up to 35 T and the temperature dependencies of the resistance of honeycomb-shape carbon networks were measured in the temperature range 2– 300 K . Two transport mechanisms were found in these systems: the hopping conductivity in the strong localization (SL) regime and weak localization (WL) in the diffusive transport limit. A crossover from SL to WL regime was observed with the temperature increasing. The temperature dependence of the resistance follows a typical for 3D-WL law R ∼ T − n in the temperature range 100–300 and 5– 300 K for networks annealed at 950°C and 1150°C, respectively. The negative magnetoresistance (NMR) observed at T >100 and 25 K , depending on the temperature of annealing of the samples, is related to quantum interference in the WL regime. The positive magnetoresistance observed in the low-temperature range was due to the magnetic field induced shrinkage of the electronic wave functions.