Theory of shot noise in single-walled metallic carbon nanotubes weakly coupled to nonmagnetic and ferromagnetic leads

We present a theoretical study of shot noise in single-walled metallic carbon nanotubes weakly coupled to either nonmagnetic or ferromagnetic leads. Using the real-time diagrammatic technique, we calculate the current, Fano factor, and tunnel magnetoresistance in the sequential tunneling regime. It is shown that the differential conductance displays characteristic fourfold periodicity, indicating single-electron charging. Such a periodicity is also visible in tunnel magnetoresistance of the system as well as in the Fano factor. The present studies elucidate the impact of ferromagnetic (vs nonmagnetic) contacts on the transport characteristics under consideration.