Mimicking synaptic plasticity with wedged Pt/Co/Pt spin-orbit torque device

TL;DR

This paper demonstrates a wedge-shaped Pt/Co/Pt device that mimics synaptic plasticity by using spin-orbit torque to achieve multiple nonvolatile magnetic states, offering a promising approach for spintronic artificial synapses.

Contribution

It introduces a novel wedge-shaped Pt/Co/Pt device capable of tunable, nonvolatile magnetic states driven solely by spin-orbit torque, mimicking synaptic plasticity.

Findings

Achieved magnetic switching without magnetic field.

Demonstrated multiple nonvolatile states with pulse currents.

Studied synaptic plasticity phenomena like STDP.

Abstract

We fabricated a wedge-shaped Pt/Co/Pt device with perpendicular magnetic anisotropy and manifested that the Co magnetization can be solely switched by spin-orbit torque without any magnetic field. Similar to the synaptic weight, we observed that the state of Co magnetization (presented by the anomalous Hall resistance RH) of the wedged Pt/Co/Pt device can be tuned continuously with a large number of nonvolatile levels by applied pulse currents. Furthermore, we studied the synaptic plasticity of the wedged Pt/Co/Pt device, including the excitatory postsynaptic potentials or inhibitory postsynaptic potentials and spiking-time-dependent plasticity. The work elucidates the promise of the wedged Pt/Co/Pt device as a candidate for a new type of artificial synaptic device that is induced by a spin current and paves a substantial pathway toward the combination of spintronics and synaptic devices.