Energy-efficient polarity reversal of a target skyrmion driven by spin-transfer effect

Abstract We investigated the current-induced polarity reversal for a ground-state target skyrmion in a spin-valve nanopillar structure, demonstrating two reversal modes distinguished by current density. In view of the considerable write energy consumption (ΔE) caused by Joule heating effect, we proposed a multivariate optimization method considering the coupling of the current density, the applied area and the effective excitation time. This optimization can significantly improve the system stability and reduce ΔE to about 30% without sacrificing reversal efficiency. Our results explain the physical origin of polarity reversal of target skyrmion and overcome a major difficulty for the practical application of skyrmionic spin structures as high-density elements in memory devices.