Abstract of Skyrmionic Spin Structures in Layered Fe5GeTe2 Up To Room Temperature

Maurice Schmitt¹, Thibaud Denneulin², András Kovács², Tom G. Saunderson^1,4, Philipp Rüßmann^3,4, Aga Shahee¹, Tanja Scholz⁵, Amir Tavabi², Martin Gradhand^1,6, Phivos Mavropoulos⁷, Bettina V. Lotsch^5,8, Rafal Dunin-Borkowski², Yuriy Mokrousov⁴, Stefan Blügel⁴, and Mathias Kläui^1,9

1 Johannes Gutenberg Universität Mainz, Institut für Physik, Staudingerweg 7, 55128 Mainz, Germany
2 Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
3 Institute of Theoretical Physics and Astrophysics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
4 Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
5 Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
6 University of Bristol, School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, England
7 National and Kapodistrian University of Athens, Department of Physics, University Campus, GR-157 84 Zografou, Athens, Greece
8 Department of Chemistry, University of Munich (LMU), Butenandtstraße 5-13 (Haus D), 81377 München, Germany
9 QuSpin, Norwegian University of Science and Technology, Department of Physics, NTNU NO-7491, Trondheim, Norway

The role of the crystal lattice, temperature and magnetic field for the spin structure formation in the 2D van der Waals magnet Fe5GeTe2 with magnetic ordering up to room temperature 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 centrosymmetry. These skyrmions can be observed even in the absence of external fields. To understand the complex magnetic order in Fe5GeTe2 we compare macroscopic magnetometry characterization results with microscopic density functional theory and spin-model calculations. Our results show that even up to room temperature, topological spin structures can be stabilized in centrosymmetric van der Waals magnets.

Reference
[1] M. Schmitt et al. arXiv:2204.11348 (2022)