Skyrmion Lattice Order Controlled by Confinement Geometry

TL;DR

This study shows how the shape of confinement geometries can control the order of skyrmion lattices in thin films, enabling better management of their phase behavior for spintronic applications.

Contribution

It introduces geometric confinement as a method to regulate skyrmion lattice order, combining experiments and simulations to demonstrate boundary effects on 2D skyrmion phases.

Findings

Hexagonal confinement stabilizes monodomain hexagonal skyrmion lattices.

Incommensurate geometries lead to domain formation and reduced order.

Confinement geometry critically influences skyrmion lattice stability.

Abstract

Magnetic skyrmions forming two-dimensional (2D) lattices provide a versatile platform for investigating phase transitions predicted by Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory. While 2D melting in skyrmion systems has been demonstrated, achieving controlled ordering in skyrmion lattices remains challenging due to pinning effects from a non-uniform energy landscape, which often results in polycrystalline structures. Skyrmions in thin films, however, offer thermal diffusion with high tunability and can be directly imaged via Kerr microscopy, enabling real-time observation of their dynamics. To regulate lattice order in such flexible systems, we introduce geometric confinements of varying shapes. Combining Kerr microscopy experiments with Thiele model simulations, we demonstrate that confinement geometry critically influences lattice order. Specifically, hexagonal confinements commensurate with the skyrmion lattice stabilize monodomain hexagonal ordering, while incommensurate geometries induce domain formation and reduce overall order. Understanding these boundary-driven effects is essential for advancing the study of 2D phase behavior and for the design of skyrmion-based spintronic applications, ranging from memory devices to unconventional computing architectures.