Properties and dynamics of meron topological spin textures in the two-dimensional magnet CrCl3

Mathias Augustin,Kostya S Novoselov,Elton J G Santos,Richard F L Evans,Sarah Jenkins

doi:10.1038/s41467-020-20497-2

Abstract

Merons are nontrivial topological spin textures highly relevant for many phenomena in solid state physics. Despite their importance, direct observation of such vortex quasiparticles is scarce and has been limited to a few complex materials. Here, we show the emergence of merons and antimerons in recently discovered two-dimensional (2D) CrCl3 at zero magnetic field. We show their entire evolution from pair creation, their diffusion over metastable domain walls, and collision leading to large magnetic monodomains. Both quasiparticles are stabilized spontaneously during cooling at regions where in-plane magnetic frustration takes place. Their dynamics is determined by the interplay between the strong in-plane dipolar interactions and the weak out-of-plane magnetic anisotropy stabilising a vortex core within a radius of 8–10 nm. Our results push the boundary to what is currently known about non-trivial spin structures in 2D magnets and open exciting opportunities to control magnetic domains via topological quasiparticles.

Highlights

Merons are nontrivial topological spin textures highly relevant for many phenomena in solid state physics
The strict 2D nature of the layers leads to unique physical properties ranging from stacking dependent interlayer magnetism[5,6], giant tunneling magnetoresistance[7,8], and second harmonic generation[9], up to electric field control of magnetic properties[10]
We demonstrate that monolayer CrCl3 hosts merons and antimerons in its magnetic structure. Both quasiparticles are created naturally during zero-field cooling at low temperatures. We find that both spin textures are directly associated with the metastability of the magnetic domains on CrCl3 induced by spin fluctuations

Summary

Introduction

Merons are nontrivial topological spin textures highly relevant for many phenomena in solid state physics. The number of dark and bright spin textures formed during the cooling at zero field is even indicating some equilibrium on the different signs of Sz. A similar nucleation process happened at a finite magnetic field perpendicular to the surface within the range of 5–10 mT (Supplementary Fig. S2). In the case of merons and antimerons with similar core polarization (Fig. 3d–f and Supplementary Movie S5), there is an enlargement of the area with out-of-plane magnetization as both topological quasiparticles approach each other.

Results

Conclusion