Spin and charge quantum pumping in zigzag silicene nanoribbon and investigating the effect of width on pumped currents

We study quantum charge and spin pumping in a graphene nanoribbon under two dephase ac gate voltages by using non-equilibrium Green’s function method. Our proposed device consists of two leads and a channel with ferromagnetic insulator. We find that, the device can pump fully spin polarized current and the spin polarization can be easily tuned by setting the Fermi energy. We also investigate the effects of width zigzag silicene nanoribbons ZSNR and compare them with zigzag graphene nanoribbon GNR and show that the pumped charge current in the ZSNR is nearly the same for odd and even numbers of silicon chains but in the zigzag graphene nanoribbon ZGNR strongly depends on nanoribbon width such that the maximum pumped current for width with even numbers of carbon chains is at least five times larger than that with odd numbers.