HALL-EFFECT AND MAGNETORESISTANCE OF CARBON NANOTUBE FILMS

We report Hall coefficient (R(H)) and magnetoresistance (Delta rho/rho ) measurements on thin films of aligned carbon nanotubes. R(H) is posi tive in the whole temperature range (1.7-300 K) showing the predominan ce of hole transport in the electronic conduction. The upper limit of the carrier concentration is 1.6x10(19) cm(-3). The resistance of the thin-film samples is governed mainly by the loose tube-tube contacts a nd this shows up in the Delta rho/rho<0 at low fields, suggesting a no ncoherent transport between the nanotubes.