Interface-generated spin currents

Transport calculations based on ab-initio band structures reveal large interface-generated spin currents at Co/Pt, Co/Cu, and Pt/Cu interfaces. These spin currents are driven by in-plane electric fields but flow out-of-plane, and can have similar strengths to spin currents generated by the spin Hall effect in bulk Pt. Each interface generates spin currents with polarization along \(\bf{\hat{z}} \times \bf{E}\), where \(\bf{\hat{z}}\) is the interface normal and \(\bf{E}\) denotes the electric field. The Co/Cu and Co/Pt interfaces additionally generate spin currents with polarization along \(\bf{\hat{m}} \times (\bf{\hat{z}} \times \bf{E})\), where \(\bf{\hat{m}}\) gives the magnetization direction of Co. The latter spin polarization is controlled by---but not aligned with---the magnetization, providing a novel mechanism for generating spin torques in magnetic trilayers.