Coherent Spintronic Networks for Neuromorphic Computing

Neuromorphic computing uses networks of artificial neurons highly interconnected by artificial synapses to perform vast data processing tasks with unmatched efficiency, as needed, for instance, for pattern recognition or autonomous driving tasks. The synaptic connections play a paramount role to create better hardware realizations of these networks. However, it is very complex to realize large interconnectivity by electronic circuitry. COSPIN overcomes this connectivity constraint by using the eigen-excitations of the magnetic system - the spin waves - to connect state-of-the-art artificial neurons based on spintronic auto-oscillators. COSPIN’S main goal is to create and experimentally validate innovative physical building blocks for a novel nano-scaled, all-spintronic network structure which incorporates all necessary properties for neuromorphic computing including high nonlinearity, interconnectivity and reprogrammability. By design, COSPIN works at the boundary between oscillator-based computing and wave-based computing. It uses interference, frequency-multiplexing, and time-modulation techniques as well as spin-wave amplification to significantly increase the connectivity between neurons. Reprogramming of the network is implemented by a direct physical link to magnetic memory solutions as well as by reconfiguring spin-wave circuits. By using coherent wave interference and nonlinear wave interaction, COSPIN paves the way for novel coupling phenomena for complex artificial neural networks far beyond the state-of-the-art of current hardware realizations. Using cutting-edge micromagnetic simulations enhanced by inverse design methods, the artificial networks will be designed and tested prior to their nano-fabrication. Experimental investigations will be mainly carried out using micro-focus Brillouin light scattering. This allows for local investigation of the individual neurons and synapses, and significantly simplifies the interpretation of the network dynamics.