Maximizing spin-orbit torque generated by the spin Hall effect of Pt

Efficient generation of spin–orbit torques is central for the exciting field of spin-orbitronics. Platinum, the archetypal spin Hall material, has the potential to be an outstanding provider for spin–orbit torques due to its giant spin Hall conductivity, low resistivity, high stabilities, and the ability to be compatible with CMOS circuits. However, pure clean-limit Pt with low resistivity still provides a low damping-like spin–orbit torque efficiency, which limits its practical applications. The efficiency of spin–orbit torque in Pt-based magnetic heterostructures can be improved considerably by increasing the spin Hall ratio of Pt and the spin transmissivity of the interfaces. Here we review recent advances in understanding the physics of spin current generation, interfacial spin transport, and the metrology of spin–orbit torques and summarize progress toward the goal of Pt-based spin–orbit torque memories and logic that are fast, efficient, reliable, scalable, and nonvolatile.