Tunable spin-polarized transport through a side-gated double quantum dot molecular junction in the Coulomb blockade regime

Based on nonequilibrium Green's function method, we investigate spin-polarized transport properties of a side-gated double quantum dot (DQD) system in the Coulomb blockade regime under a magnetic field and an electric or thermal bias. The charge and spin currents oscillate frequently and can change sign upon varying gate voltage $V_{\text{G}}$ if the electric bias is spin–dependent. Under a thermal bias, besides the charge- and spin-current oscillations with $V_{\text{G}}$, a pure spin current appears at the electron–hole symmetry point. Importantly, its sign can be controlled by the magnetic field above a "critical" strength. In addition, the charge- and spin-Seebeck coefficients oscillate nontrivially depending on $V_{\text{G}}$, $B$, and the tunnel coupling. Finally, we also study the spin-polarized transport properties of the DQD system effects under simultaneously applying an electric and a thermal bias.