Skyrmionic Spin Structures in Layered Fe5GeTe2 Up To Room Temperature

TL;DR

This study demonstrates the formation and stability of skyrmionic spin structures in the 2D van der Waals magnet Fe5GeTe2 up to room temperature, revealing their independence from chirality and external fields.

Contribution

It provides experimental evidence of skyrmionic structures in Fe5GeTe2 at room temperature and links microscopic and macroscopic magnetic properties in a centrosymmetric 2D magnet.

Findings

Skyrmionic bubbles observed up to room temperature.

Bubbles form without external magnetic field in pre-cooling phase.

Transformation from bubbles to stripe domains after cooling.

Abstract

The role of the crystal lattice, temperature and magnetic field for the spin structure formation in the 2D van der Waals magnet Fe5GeTe2 is a key open question. Using Lorentz transmission electron microscopy, we experimentally observe topological spin structures up to room temperature in the metastable pre-cooling and stable post-cooling phase of Fe5GeTe2. Over wide temperature and field ranges, skyrmionic magnetic bubbles form without preferred chirality, which is indicative of a centrosymmetric crystal structure. In the pre-cooling phase, these bubbles are observable even without the application of an external field, while in the post-cooling phase, a transformation from bubble domains to stripe domains is seen. To understand the magnetic order in Fe5GeTe2 we compare macroscopic magnetometry characterization results with microscopic density functional theory calculation. Our results show that even up to room temperature, topological spin structures can be stabilized in centrosymmetric van der Waals magnets.