Linked skyrmions in shifted magnetic bilayer

TL;DR

This paper introduces a shifted magnetic bilayer system capable of hosting linked skyrmions with large topological charges, expanding the understanding and potential applications of magnetic solitons.

Contribution

It demonstrates the existence of linked skyrmions with arbitrary large topological charges in a shifted bilayer, including novel configurations like skyrmion-bags and $k ext{ extpi}$-skyrmions.

Findings

Linked skyrmions with large topological charges can be stabilized.

Tuning interlayer exchange and magnetic field yields different ground states.

Proposed material candidate for realizing these magnetic configurations.

Abstract

Magnetic solitons have recently attracted significant attention due to their intricate physical properties and potential applications in information processing. The majority of the studies in this field, however, are focused on a particular type of solitons known as skyrmions, characterised by a unit topological charge. Here, we present a shifted magnetic bilayer that can demonstrate magnetic solitons with arbitrary large topological charges. These configurations, which we call linked skyrmions, consist of multiple skyrmions linked together with topological point defects. These topological point defects, termed as anti-aligned points, originate from the mutually orthogonal Dzyaloshinskii-Moriya interaction in two different layers. By tuning the interlayer exchange coupling and the external magnetic field, one can also achieve different ground states in this bilayer. Additionally, the system also demonstrates conventional skyrmion-bags and $k\pi$-skyrmions. Finally we propose a suitable material candidate where these magnetic configurations can be realised. Our findings, thus, can provide a way to achieve solitons with large topological charge and realise them in realistic systems.