Spin-orbit torques: Materials, physics, and devices

TLDR

Spintronics leverages electron spin to create novel microelectronic devices, notably magnetic random‑access memory, and recent work has focused on spin‑orbit torque as a means to manipulate magnetization for ultrafast, energy‑efficient MRAM. This Perspective reviews recent advances in spin‑orbit torque and identifies key technical challenges for bringing practical SOT devices to fruition. The authors outline field‑free deterministic SOT switching techniques, discuss the materials employed, and survey recent progress in SOT‑MRAM, spin logic, nano‑oscillators, and neuromorphic applications.

Abstract

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.