Magnetoresistance of ferromagnetically contacted carbon nanotubes

Magnetoresistance measurements of multi-walled carbon nanotubes having one or two ferromagnetic contacts are compared. Nanotubes with two cobalt contacts show hysteretic switching in the magnetoresistance, with a maximum change of 9% at View the MathML source, while nanotubes with one cobalt contact and one platinum/gold contact show no magnetoresistance switching. This provides further evidence for coherent transport of electron spin through the multi-walled nanotube. In addition, the magnetoresistance ratio in the ferromagnetic nanotube device is calculated for a two-band ballistic model, and gives a maximum value of 25%.