Parametric quantum spin pump

We investigate a nonadiabatic parametric quantum pump consisting of a nonmagnetic scattering region connected by two ferromagnetic leads. The presence of ferromagnetic leads allows electrons with different spins to experience different potential landscapes. Using this effect we propose a quantum spin pump that drives spin-up electrons to flow in one direction and spin-down electrons to flow in opposite direction. As a result, the spin pump can deliver a spin current with a vanishing charge current.