Impurity effects on the spin-polarized transport through armchair carbon nanotubes contacted by ferromagnetic leads are investigated theoretically. The length of the nanotube can cause on-resonance and off-resonance behaviors of the spin-coherent transport. The impurity suppresses the...

We theoretically study the spin pump effects of the rotating magnetic field on the spin current through two coupled quantum dots. Owing to the interdot coupling, two molecular states with different bands can be formed, resulting asymmetric spin current peaks. The possibility of manipulating the...

The supercurrent through an Aharonov-Bohm interferometer containing two parallel quantum dots connected with two superconductor leads is investigated theoretically. The possibility of controlling the supercurrent is explored by tuning the quantum dot energy levels and the total magnetic flux. By...