Spin-flip mesoscopic transport through a toroidal carbon nanotube coupled to normal metal terminals

The spin and charge currents tunnelling through coupled toroidal carbon nanotube (TCN) system is investigated in the presence of rotating magnetic field and an Aharonov-Bohm magnetic flux. The charge current and spin current coexist in the same system as eV≠0. The charge conductance, charge current, and spin current are sensitively determined by the applied magnetic fields and the quantum nature of coupled TCN system. Zeeman splitting and spin-flip effect make different contributions to the spin and charge currents due to symmetrically energy splitting and asymmetric resonant behavior. The spin current is strongly adjusted by the frequency of rotating field, which is associated with the photon-absorption and resonance procedure in TCN.