Controllable Creation of Skyrmion Bags in a Ferromagnetic Nanodisk

TL;DR

This paper proposes a three-step method to create skyrmion bags with high topological charge in ferromagnetic nanodisks, combining magnetic field, local current injection, and potential reconstruction, with simulated microscopy images to guide experiments.

Contribution

It introduces a novel method for creating skyrmion bags in magnetic films, enabling controlled topological charge and potential spintronic applications.

Findings

Skyrmion bags with topological charge up to forty can be generated.

Simulated microscopy images support experimental realization.

The method combines magnetic field, current injection, and potential reconstruction.

Abstract

Skyrmion bags are composed of an outer skyrmion and arbitrary inner skyrmions, which have recently been observed in bulk chiral magnets, but still remain elusive in magnetic films. Here, we propose a method of creating skyrmion bags in a thin-film nanodisk, which includes three steps. Firstly, the size of outer skyrmion is enlarged by a vertical magnetic field, then inner skyrmions are nucleated at an off-center area by local current injection, and the system is finally reconstructed due to multiple inter-skyrmion potentials. Thus, skyrmion bags with topological charge up to forty can be created. Simulated Lorentz transmission electron microscopy images are given to facilitate the experimental demonstration. Our proposal is expected to inspire relevant experiments in magnetic films, and pave the way for potential spintronic applications based on skyrmion bags.