Spin injection into carbon nanotubes and a possible application in spin-resolved scanning tunnelling microscopy

We present magnetotransport measurements on multiwall nanotubes contacted by ferromagnetic electrodes that are 1 µm apart. The observed magnetoresistance of 2.2% is consistent with a spin-scattering length of at least 380 nm. We further discuss a novel concept for spin-resolved scanning tunnelling microscopy (SR-STM) with a carbon-nanotube tip. The concept relies on a long spin-scattering length as well as on spin-dependent scattering at the interfaces to the ferromagnetic electrodes. The observed magnitude of the magnetoresistance effect and the distance between the electrodes are large enough for application in a SR-STM.