Adiabatic charge and spin pumping through quantum dots with ferromagnetic leads

We study the adiabatic pumping of electrons through quantum dots attached to ferromagnetic leads. Hereby, we make use of a real-time diagrammatic technique in the adiabatic limit that takes the strong Coulomb interaction in the dot into account. We analyze the degree of spin polarization of electrons pumped from a ferromagnet through the dot to a nonmagnetic lead (N-dot-F) as well as the dependence of the pumped charge on the relative leads' magnetization orientations for a spin-valve (F-dot-F) structure. For the former case, we find that, depending on the relative coupling strength to the leads, spin and charge can, on average, be pumped in opposite directions. For the latter case, we find an angular dependence of the pumped charge, which becomes more and more anharmonic for large spin polarization in the leads.