Interfacial spin-orbit torque and spin transparency in Co/Pt bilayer

We show that interfacial spin–orbit coupling is an efficient source of spin-orbit torques in a Co/Pt bilayer, a prototypical spin-orbitronic device. We find that the spin–orbit coupling at the Co/Pt interface can be effectively manipulated by inserting a thin TiN layer. We show that the strong spin–orbit coupling at the Co/Pt interface enables efficient generation of interfacial spin-orbit torques, as well as suppresses bulk spin-orbit torques, resulting in the dominance of the interfacial contribution in the generation of the spin-orbit torques. This result provides an important information for developing efficient spin-orbitronic devices based on the interfacial spin–orbit coupling.