Skyrmions and magnetic bubbles in spin-orbit coupled metallic magnets

TL;DR

This paper presents a microscopic model for magnetic textures in 2D ferromagnets, revealing how Skyrmions and magnetic bubbles emerge and transition under magnetic fields and anisotropy, aligning with experimental observations.

Contribution

It introduces a new model combining itinerant magnetism and spin-orbit coupling that explains the formation of Skyrmions and magnetic bubbles in 2D magnetic materials.

Findings

Filamentary magnetic domain walls in the model match experimental microscopy images.

Magnetic field causes filaments to break into magnetic bubbles.

Uniaxial magnetic anisotropy controls the transition between Skyrmions and bubbles.

Abstract

Motivated by the observation of Skyrmion-like magnetic textures in 2D itinerant ferromagnets Fe$_n$GeTe$_2$ ($n \geq3$), we develop a microscopic model combining itinerant magnetism and spin-orbit coupling on a triangular lattice. The ground state of the model in the absence of magnetic field consists of filamentary magnetic domain walls revealing a striking similarity with our magnetic force microscopy experiments on Fe$_3$GeTe$_2$. In the presence of magnetic field, these filaments were found to break into large size magnetic bubbles in our experiments. We identify uniaxial magnetic anisotropy as an important parameter in the model that interpolates between magnetic Skyrmions and ferromagnetic bubbles. Consequently, our work uncovers new topological magnetic textures that merge properties of Skyrmions and ferromagnetic bubbles.