Observation of memristive domain patterns during spin-orbit torque switching in antiferromagnet/ferromagnet heterostructures

摘要

Efficient field-free spin-orbit torque (SOT) magnetization switching has been achieved by use of antiferromagnet (AFM)/ferromagnet (FM) structures. In addition, use of the AFM in them leads to formation of reproducible analogue-like (or "memristive") switching with multiple nonvolatile states. These properties allowed using such structures in an artificial-neural-network-based associative memory. Additional electrical measurements suggested that the memristivity originates from separate switching of binary domains of 200 nm scale, which is nonsimultaneous due to exchange bias (EB) variation. The described picture differs from the conventional SOT switching in nonmagnet (NM)/FM heterostructures and its deeper understanding is important for fundamental research of SOT and EB as well as applications.