Spin-dependent transport through a single-walled carbon nanotube coupled to a ferromagnetic and a nonmagnetic metal electrode

We report on transport measurements of an individual single-walled carbon nanotube (SWNT) coupled to a ferromagnetic and a nonmagnetic metal electrode. The low-temperature differential conductance shows a suppression of zero-bias conductance and Coulomb blockade oscillations, where the metallic SWNT behaves as a quantum dot. A marked hysteretic magnetoresistance is observed within the coercive region of the ferromagnetic metal film. The differential resistance has distinctly different values when the magnetization orientation is reversed. Our observed data suggest that the spin-split density of states lies within the SWNT quantum dot. We present an Anderson Hamiltonian to model the spin-polarized electron transport through the SWNT quantum dot with spin-split discrete levels, which supports the experimental observation.