Interface-Enhanced Spin-Orbit Torques and Current-Induced Magnetization Switching of Pd/Co/AlOx Layers

Magnetic heterostructures that combine large spin-orbit torque efficiency, perpendicular magnetic anisotropy, and low resistivity are key to developing electrically controlled memory and logic devices. Here, we report on vector measurements of the current-induced spin-orbit torques and magnetization switching in perpendicularly magnetized Pd/Co/AlOx layers as a function of Pd thickness. We find sizable dampinglike (DL) and fieldlike (FL) torques, on the order of 1 mT per 10(7) A/cm(2), which have different thicknesses and magnetization angle dependencies. The analysis of the DL torque efficiency per unit current density and the electric field using drift-diffusion theory leads to an effective spin Hall angle and spin-diffusion length of Pd larger than 0.03 and 7 nm, respectively. The FL spin-orbit torque includes a significant interface contribution, is larger than estimated using drift-diffusion parameters, and, furthermore, is strongly enhanced upon rotation of the magnetization from the out-of-plane to the in-plane direction. Finally, taking advantage of the large spin-orbit torques in this system, we demonstrate bipolar magnetization switching of Pd/Co/AlOx layers with a similar current density to that used for Pt/Co layers with a comparable perpendicular magnetic anisotropy.