Neuromorphic Computing with Emerging Antiferromagnetic Ordering in Spin–Orbit Torque Devices
Durgesh Kumar Ojha, Yu‐Hsin Huang, Yu-Lon Lin, Ratnamala Chatterjee, Wen-Yueh Chang, Yuan‐Chieh Tseng
Abstract
High Resolution Image Download MS PowerPoint Slide Field-free switching (FFS) and spin–orbit torque (SOT)-based neuromorphic characteristics were realized in a W/Pt/Co/NiO/Pt heterostructure with a perpendicular exchange bias ( H EB ) for brain-inspired neuromorphic computing (NC). Experimental results using NiO-based SOT devices guided the development of fully spin-based artificial synapses and sigmoidal neurons for implementation in a three-layer artificial neural network. This system achieved impressive accuracies of 91–96% when applied to the Modified National Institute of Standards and Technology (MNIST) image data set and 78.85–81.25% when applied to Fashion MNIST images, due presumably to the emergence of robust NiO antiferromagnetic (AFM) ordering. The emergence of AFM ordering favored the FFS with an enhanced H EB, which suppressed the memristivity and reduced the recognition accuracy. This indicates a trade-off between the requirements for solid-state memory and those required for brain-inspired NC devices. Nonetheless, our findings revealed opportunities by which the two technologies could be aligned via controllable exchange coupling.