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

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 R H ) 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.