# Paths to collapse for isolated skyrmions in few-monolayer ferromagnetic films

## TL;DR

This paper analyzes the collapse mechanisms of isolated skyrmions in ultrathin ferromagnetic films, revealing how multilayer structure and boundary effects influence their stability, with implications for magnetic storage technologies.

## Contribution

It presents a minimum-energy path analysis of skyrmion collapse mechanisms in atomic-layer ferromagnetic films using ab initio and atomic-spin simulations, highlighting stability factors.

## Key findings

- Boundary effects reduce skyrmion stability in finite systems.
- Designing multilayers with varying DMI improves skyrmion stability.
- Collapse mechanisms depend on multilayer structure and geometry.

## Abstract

Magnetic skyrmions are topological spin configurations in materials with chiral Dzyaloshinskii-Moriya interaction (DMI), that are potentially useful for storing or processing information. To date, DMI has been found in few bulk materials, but can also be induced in atomically thin magnetic films in contact with surfaces with large spin-orbit interactions. Recent experiments have reported that isolated magnetic skyrmions can be stabilized even near room temperature in few-atom thick magnetic layers sandwiched between materials that provide asymmetric spin-orbit coupling. Here we present the minimum-energy path analysis of three distinct mechanisms for the skyrmion collapse, based on ab initio input and the performed atomic-spin simulations. We focus on the stability of a skyrmion in three atomic layers of Co, either epitaxial on the Pt(111) surface, or within a hybrid multilayer where DMI nontrivially varies per monolayer due to competition between different symmetry-breaking from two sides of the Co film. In laterally finite systems, their constrained geometry causes poor thermal stability of the skyrmion toward collapse at the boundary, which we show to be resolved by designing the high-DMI structure within an extended film with lower or no DMI.