Hall effect and magnetoresistance of carbon nanotube films

We report Hall coefficient (${\mathrm{R}}_{\mathrm{H}}$ ) and magnetoresistance (Δρ/ρ) measurements on thin films of aligned carbon nanotubes. ${\mathrm{R}}_{\mathrm{H}}$ is positive in the whole temperature range (1.7–300 K) showing the predominance of hole transport in the electronic conduction. The upper limit of the carrier concentration is 1.6×${10}^{19}$ ${\mathrm{cm}}^{\mathrm{-}3}$ . The resistance of the thin-film samples is governed mainly by the loose tube-tube contacts and this shows up in the Δρ/ρ<0 at low fields, suggesting a noncoherent transport between the nanotubes.