Interface-generated spin currents

Abstract

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 $\hat{\mathbf{z}}\times \mathbf{E}$, where $\hat{\mathbf{z}}$ is the interface normal and $\mathbf{E}$ denotes the electric field. The Co/Cu and Co/Pt interfaces additionally generate spin currents with polarization along $\hat{\mathbf{m}}\times (\hat{\mathbf{z}}\times \mathbf{E})$, where $\hat{\mathbf{m}}$ 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.