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

The magnetoresistance (MR) in the magnetic fields up to View the MathML source and the temperature dependencies of the resistance of honeycomb-shape carbon networks were measured in the temperature range 2–View the MathML source. 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–View the MathML source for networks annealed at 950°C and 1150°C, respectively. The negative magnetoresistance (NMR) observed at T>100 and View the MathML source, 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.