Spin transport in nanotubes

We present transport measurements of ferromagnetically contacted carbon nanotubes. The resistance of a ferromagnetically contacted multi-walled nanotube switches hysteretically as a function of applied magnetic field, with a maximum resistance change of 9% at 4.2 K. Our observed magnetoresistance suggests that spin polarized current is injected into the carbon nanotube and conduction occurs without randomization of the spin polarization. Background details of the spin transport mechanism are discussed.