Theory of isolated magnetic skyrmions: From fundamentals to room temperature applications

TLDR

Magnetic skyrmions are topological quasiparticles of interest for data storage due to their small size, high stability, and ease of manipulation, yet no universal theory accurately describes their structure and energetics because of complex non‑local stray field interactions that are usually crudely approximated. Here we present an accurate analytical framework to treat isolated skyrmions in any material, assuming a circularly‑symmetric 360° domain wall profile and a homogeneous out‑of‑plane magnetization. The framework analytically models isolated skyrmions using this domain‑wall assumption and derives equations for current‑driven dynamics, revealing topological damping and enabling design of materials that allow velocities above 1000 m/s. We establish rigorous criteria distinguishing stray‑field from DMI skyrmions, uncover new bi‑stable phases, predict sub‑10 nm zero‑field room‑temperature stable skyrmions, and provide analytical equations for high‑velocity dynamics.

Abstract

Magnetic skyrmions are topological quasiparticles of great interest for data storage applications because of their small size, high stability, and ease of manipulation via electric current. However, although models exist for some limiting cases, there is no universal theory capable of accurately describing the structure and energetics of all skyrmions. The main barrier is the complexity of non-local stray field interactions, which are usually included through crude approximations. Here we present an accurate analytical framework to treat isolated skyrmions in any material, assuming only a circularly-symmetric 360° domain wall profile and a homogeneous magnetization profile in the out-of-plane direction. We establish the first rigorous criteria to distinguish stray field from DMI skyrmions, resolving a major dispute in the community. We discover new phases, such as bi-stability, a phenomenon unknown in magnetism so far. We predict materials for sub-10 nm zero field room temperature stable skyrmions suitable for applications. Finally, we derive analytical equations to describe current-driven dynamics, find a topological damping, and show how to engineer materials in which compact skyrmions can be driven at velocities >1000 m/s.