Atomistic Study of Traveling Skyrmions in Multi-Sublattice Magnetic Materials

Abstract

The development of novel energy-efficient computing hardware is imperative for the reduction of the carbon footprint and for the extension of computing, mobile and wearable device lifespan. Recent advances have been focused on turning to novel material systems, and one such avenue is magnetic thin films. Bits of information can be encoded by magnetic twisted textures called skyrmions, which can be efficiently driven by applying electrical current. Recently, emphasis has been placed on investigating antiferromagnetic and ferrimagnetic skyrmions, as opposed to the single-sublattice ferromagnetic ones studied earlier, due to their potential for more rapid dynamics and magnetic stability. However, there is a pressing need for a thorough and detailed understanding of the intricacies of skyrmion motion, in particular, limiting velocity, optimization of trajectory, controlled mobility and, notably, the observed dynamic distortions of skyrmion profiles. For this reason, experimental studies are simply not enough to provide a complete picture, since the material parameter space for systems hosting skyrmions is quite large. We perform a comprehensive study combining simulation-based as well as analytical approaches, of the spin-orbit torque motion of skyrmions in a wide host of magnetic materials, ranging from crystalline antiferromagnetic to ferrimagnetic, to ferromagnetic. We systematically analyze the relationship between physical distortions of the skyrmion profiles, based on the action of local Thiele forces, and internal elastic tension forces, providing a quantitative and nuanced explanation of these effects. These results expand the understanding of fundamental properties of magnetic skyrmions, as well as their potential use in spintronics applications.