Thermal Stability of Skyrmion Tubes in Nanostructured Cuboids

TL;DR

This study visualizes and analyzes the stability of three-dimensional skyrmion tubes in nanostructured cuboids of FeGe, revealing their stabilization near the Curie temperature and the influence of thermal fluctuations, advancing spintronic device development.

Contribution

First direct imaging of skyrmion tubes in nanostructured cuboids and analysis of their stabilization mechanisms near the Curie temperature.

Findings

Skyrmion tubes stabilize near the Curie temperature under an in-plane magnetic field.

Metastable skyrmion tubes can be maintained over a broader temperature range via field cooling.

Thermal fluctuations and energy differences influence skyrmion tube stability.

Abstract

Magnetic skyrmions in bulk materials are typically regarded as two-dimensional structures. However, they also exhibit three-dimensional configurations, known as skyrmion tubes, which elongate and extend in-depth. Understanding the configurations and stabilization mechanism of skyrmion tubes is crucial for the development of advanced spintronic devices. However, the generation and annihilation of skyrmion tubes in confined geometries are still rarely reported. Here, we present direct imaging of skyrmion tubes in nanostructured cuboids of a chiral magnet FeGe using Lorentz transmission electronic microscopy (TEM), while applying an in-plane magnetic field. It is observed that skyrmion tubes stabilize in a narrow field-temperature region near the Curie temperature (Tc). Through a field cooling process, metastable skyrmion tubes can exist in a larger region of the field-temperature diagram. Combining these experimental findings with micromagnetic simulations, we attribute these phenomena to energy differences and thermal fluctuations. Our results could promote topological spintronic devices based on skyrmion tubes.