Spin-dependent transport properties in a single-walled carbon nanotube with mesoscopic Co contacts

We have studied the spin-dependent transport properties of single-walled carbon nanotubes having the mesoscopic ferromagnetic Co electrodes. The resistances of Co contacted single-walled nanotubes with the voltage probe lengths of about 0.4 and $1.5\mu \mathrm{m}$ change hysteretically as a function of magnetic field, with the magnetoresistance change of 2.6%–3.4% at low temperatures, exhibiting spin-polarized electron transport. The magnetoresistance ratio was enhanced as the bias voltage decreased to the Coulomb blockade regime.