Spin-orbit torques: Materials, physics, and devices

Applied Physics Letters, Volume 118, Issue 12, March 2021. Spintronics, that is, the utilization of electron spin to enrich the functionality of microelectronics, has led to the inception of numerous novel devices, particularly magnetic random-access memory (MRAM). Over the last decade, significant effort has been devoted to magnetization manipulation using spin-orbit torque (SOT), which shows great promise for ultrafast and energy-efficient MRAM. In this Perspective, we summarize the latest progress in the study of SOT and highlight some of the technical challenges facing the development of practical SOT devices. After introducing the basic concepts of SOT and its relevance for magnetization switching, we will focus on several methods to realize deterministic SOT switching in the absence of an external field, which is a requirement for practical SOT devices. Additionally, we summarize the materials used in SOT devices. The final section is devoted to the most important recent advances in the application of SOT devices, including SOT-MRAM, spin logic, spin Hall nano-oscillators, and neuromorphic devices.