Artificial Neuron and Synapse Realized in an Antiferromagnet/Ferromagnet Heterostructure Using Dynamics of Spin–Orbit Torque Switching

Abstract

Efficient information processing in the human brain is achieved by dynamics of neurons and synapses, motivating effective implementation of artificial spiking neural networks. Here, the dynamics of spin–orbit torque switching in antiferromagnet/ferromagnet heterostructures is studied to show the capability of the material system to form artificial neurons and synapses for asynchronous spiking neural networks. The magnetization switching, driven by a single current pulse or trains of pulses, is examined as a function of the pulse width (1 s to 1 ns), amplitude, number, and pulse‐to‐pulse interval. Based on this dynamics and the unique ability of the system to exhibit binary or analog behavior depending on the device size, key functionalities of a synapse (spike‐timing‐dependent plasticity) and a neuron (leaky integrate‐and‐fire) are reproduced in the same material and on the basis of the same working principle. These results open a way toward spintronics‐based neuromorphic hardware that executes cognitive tasks with the efficiency of the human brain.

Tailoring Multilevel‐Stable Remanence States in Exchange‐Biased System through Spin‐Orbit Torque

“…Usually, the resistance variation induced by programming consecutive pulses sequences can be utilized to imitate the synaptic behaviors (e.g., to reproduce the plasticity of synapses). [ 4,5,40,41 ] Synaptic plasticity is the ability of synapses to reconfigure the strength with which they connect two neurons according to the past electrical activity of these neurons. [ 40,42 ] It allows neutral networks to learn and form memories.…”

Current‐Induced Spin–Orbit Torques for Spintronic Applications

“…For instance, it can drive domain walls or skyrmions effectively, [36,[167][168][169][170] facilitating chiral-spin-texturebased memory or logic devices. [16,83,84,90,[171][172][173][174][175] Moreover, it enables the demonstration of memristive behavior in a spintronic device, [106,164,165,[176][177][178] which can perform synaptic functions in artificial neural networks.…”

Electrical Control of Perpendicular Magnetic Anisotropy and Spin‐Orbit Torque‐Induced Magnetization Switching

“…Thus, we can conclude that through controlling the PMA via electrical field driven oxygen ion migration, the spin‐orbit torque induced magnetization switching can be controlled. Furthermore, the memristive behavior that arises from the SOT‐induced multilevel intermediate states due to partial magnetization switching also provides an attractive method for designing multi‐bit data storage43,44 and neuromorphic computing 45–47…”