Impact of Kondo correlations and spin–orbit coupling on spin-polarized transport in carbon nanotube quantum dot

Spin polarized transport through a quantum dot coupled to ferromagnetic electrodes with noncollinear magnetizations is discussed in terms of nonequilibrium Green functions formalism in the finite-U slave boson mean field approximation. The difference of orientations of the magnetizations of electrodes opens off-diagonal spin–orbital transmission and apart from spin currents of longitudinal polarization also spin-flip currents appear. We also study equilibrium pure spin current at zero bias and discuss its dependence on magnetization orientation, spin–orbit coupling strength and gate voltage. Impact of these factors on tunneling magnetoresistance (TMR) is also undertaken. In general spin–orbit coupling weakens TMR, but it can change its sign. •Tunneling magnetoresistance changes sign with the increase of the spin–orbit coupling.•Equilibrium spin current is observed for noncollinear polarized leads.•The average spin and exchange field splitting change the sign with gate voltage.•Transverse spin current changes direction with the increase of the bias voltage.