The Ferromagnetic Domain-Wall Synapse Device

In this chapter, we discuss in detail the main spintronic synapse device considered for neuromorphic computing in this book: the ferromagnetic domain-wall device. We first describe the working principle of the device and then show micromagnetics-based simulations of the same. Next, we discuss recent experimental demonstrations of the device and how the experimentally observed synaptic characteristic deviates from the micromagnetic-simulation-based prediction, particularly with respect to the linearity and symmetry of the device’s synaptic characteristic (linearity and symmetry are highly desired properties from the synapse to obtain high accuracy during on-chip learning in neuromorphic computing). Then, we show through supporting micromagnetic simulations how the experimental device structure can be modified to improve the linearity and symmetry of its synaptic characteristic. Finally, we discuss other spintronic alternatives to the domain-wall device, like the skyrmionic device.