Magnetoresistance and spin diffusion in multi-wall carbon nanotubes

Studies of the spin diffusion and magnetoresistance of multiwall carbon nanotubes contacted to by both cobalt and gold electrodes in magnetic fields of up to 4 T are reported. The measured room temperature contact resistance of the Au and Co electrodes ranged from 10(3) to 10(6) Omega. The magnetoresistance of tubes contacted to by Au electrodes and measured up to 4 T at 4.2 and 2.2 K was observed to be negative. The maximum negative magnetoresistance for the nanotubes contacted to by Co electrodes was 25%. As the temperature was increased the magnetoresistance decreased and disappeared above 25 K. The spin diffusion length was calculated to be 650 nm. (c) 2007 Elsevier B.V. All rights reserved.