Non-collinear antiferromagnetic spintronics

Abstract

Spintronics aims to go beyond the charge-based paradigm of silicon-based microelectronics by utilizing the spin degree of freedom for memory, storage and computing applications. State-of-the-art spintronic devices rely on the manipulation of magnetic textures by spin torques that are generated from electrical currents within ferromagnets (FMs) (spin-transfer torque) or proximal heavy metals (spin-orbit torque). Although these concepts have led to important commercial applications, the use of FMs poses challenges owing to their stray fields, relatively slow dynamics and limited thermal stability. To overcome these challenges, new materials are needed, especially those that display negligible stray fields such as antiferromagnets (AFs). In this regard, synthetic AFs have been vitally important since their use in the very first spintronic field sensors and memories. Collinear AFs have found applications in stabilizing magnetic textures via interfacial exchange bias. Going beyond these classes of AFs, the family of non-collinear AFs (NCAFs) with triangular spin textures has attractive properties, some of them even reminiscent of FMs. These include, for example, large anomalous Hall and Nernst effects, and substantial magneto-optical responses, despite their nearly fully compensated magnetization. Thus, one can anticipate their use in substituting FMs in future spintronic devices. Furthermore, these novel AFs convert electrical currents to spin currents with unique symmetries, which may allow for new ways to manipulate spin textures. Here, we review recent developments in non-collinear antiferromagnetic spintronics. Emphasis is placed on spin current generation, switching of spin textures and applications in magnetic random access memory and racetrack memory, as well as so-far unexplored materials. We show that although key components of spintronic devices based on NCAFs have been demonstrated, a wide range of potential materials remain to be explored and many open questions remain to be answered. Thus, the field of NCAFs is a vibrant and exciting subfield of spintronics with much potential for next-generation memory and computing technologies.