Skyrmion-based Synaptic Element with Strain-mediated Plasticity

We present a novel skyrmion-based synaptic device featuring a multilayer structure of Ferromagnetic (FM)/Heavy metal (HM)/Ferroelectric (FE)/HM/FM, specifically (Co/Pt)n/(011)PMN-PT/(Co/Pt)n. The FE layer sandwiched between the two FM layers hosting the skyrmions enables electric field-induced strain-mediated modulation of perpendicular magnetic anisotropy (PMA) in the FM layers. This mechanism facilitates tunable skyrmion sizes, achieving continuous non-volatile conductance states due to remnant strain in the FE layer. The proposed device exhibits both synaptic potentiation and depression with the aid of differential MTJ readout unlike the prior skyrmion-based synaptic implementations and exhibits superior energy-efficiency compared to the other emerging non-volatile memory-based synaptic devices. Furthermore, a VGG-8 convolutional neural network utilizing the proposed synaptic element as weights achieves an accuracy of 90.39% after training on the CIFAR-10 dataset.