Three-Dimensional Chiral Magnetization Structures in FeGe Nanospheres

TL;DR

This study uses micromagnetic simulations to explore the diverse three-dimensional chiral magnetization structures in FeGe nanospheres, revealing multiple equilibrium states and minimal dipolar interactions, with implications for multi-state memory devices.

Contribution

First detailed simulation-based analysis of 3D chiral magnetization structures in FeGe nanospheres, identifying multiple equilibrium states and their phase diagram.

Findings

Multiple stable magnetization states identified in nanospheres.

Magneto-dipolar interactions are negligible at this scale.

Phase diagram maps states as a function of field and radius.

Abstract

Skyrmions, spin spirals, and other chiral magnetization structures developing in materials with intrinsic Dzyaloshinsky-Moriya Interaction display unique properties that have been the subject of intense research in thin-film geometries. Here we study the formation of three-dimensional chiral magnetization structures in FeGe nanospheres by means of micromagnetic finite-element simulations. In spite of the deep sub-micron particle size, we find a surprisingly large number of distinct equilibrium states, namely, helical, meron, skyrmion, chiral-bobber and quasi-saturation state. The distribution of these states is summarized in a phase diagram displaying the ground state as a function of the external field and particle radius. This unusual multiplicity of possible magnetization states in individual nanoparticles could be a useful feature for multi-state memory devices. We also show that the magneto-dipolar interaction is almost negligible in these systems, which suggests that the particles could be arranged at high density without experiencing unwanted coupling.