Emergence of stable meron quartets in twisted magnets

TL;DR

This paper demonstrates that twist engineering in easy-plane magnets can produce stable meron quartets, offering a new platform for topological spin textures with enhanced stability against annihilation and external perturbations.

Contribution

The study introduces a novel method of creating stable meron quartets in twisted bilayer magnets, advancing the understanding of topological spin textures in magnetic systems.

Findings

Stable double meron pair (MQ) observed in twisted bilayer magnets.

Merons in MQ are stabilized by twist-induced localization, preventing annihilation.

Stability of MQ increases with twist angle and external magnetic fields.

Abstract

The investigation of twist engineering in easy-axis magnetic systems has revealed the remarkable potential for generating topological spin textures, such as magnetic skyrmions. Here, by implementing twist engineering in easy-plane magnets, we introduce a novel approach to achieve fractional topological spin textures such as merons. Through atomistic spin simulations on twisted bilayer magnets, we demonstrate the formation of a stable double meron pair in two magnetic layers, which we refer to as the "Meron Quartet" (MQ). Unlike merons in a single pair, which is unstable against pair annihilation, the merons within the MQ exhibit exceptional stability against pair annihilation due to the protective localization mechanism induced by the twist that prevents the collision of the meron cores. Furthermore, we showcase that the stability of the MQ can be enhanced by adjusting the twist angle, resulting in increased resistance to external perturbations such as external magnetic fields. Our findings highlight the twisted magnet as a promising platform for investigating the intriguing properties of merons, enabling their realization as stable magnetic quasiparticles in van der Waals magnets.