| Popis: |
The exceptional properties of skyrmion devices, including their miniature size, topologically protected nature, and low current requirements, render them highly promising for energy-efficient neuromorphic computing applications. Examining the creation, stability, and dynamics of magnetic skyrmions in thin-film systems is imperative to realize these skyrmion-based neuromorphic devices. Herein, we report the creation, stability, and tunability of magnetic skyrmions in the Ta/IrMn/CoFeB/MgO thin-film system. We use polar magneto-optic Kerr effect (MOKE) microscopy and micromagnetic simulations to investigate the magnetic-field dependence of skyrmion density and size. The topological charge evolution with time under a magnetic field is studied, and the transformation dynamics are explained. Furthermore, we demonstrate skyrmion size and density tunability as parameters controlled by voltage, current, and magnetic field via Voltage-Controlled Magnetoresistance (VCMA) and Dzyaloshinskii-Moriya Interaction (DMI). We propose a skyrmion-based synaptic device for neuromorphic computing applications. The device exhibits spin-orbit torque-controlled discrete topological resistance states with high linearity and uniformity, allowing for the realization of the hardware implementation of weight quantization in a Quantized Convolutional Neural Network (QCNN). Our experimental results demonstrate that the devices can be trained and tested on the CIFAR-10 dataset, achieving a recognition accuracy of ~87%. The findings open new avenues for developing neuromorphic computing devices based on tunable skyrmion systems. |
