Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2

Abstract
In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.

Citation
Ribeiro, M., Gentile, G., Marty, A., Dosenovic, D., Okuno, H., Vergnaud, C., Jacquot, J.-F., Jalabert, D., Longo, D., Ohresser, P., Hallal, A., Chshiev, M., Boulle, O., Bonell, F., & Jamet, M. (2022). Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2. Npj 2D Materials and Applications, 6(1). https://doi.org/10.1038/s41699-022-00285-w

Acknowledgements
The MBE reactors were funded by the project Minatec LABS 2018 N°2018 AURA P3 and the project EPI2D of the University Grenoble Alpes IDEX. We acknowledge the financial support from the UGA IDEX IRS/EVASPIN, the ANR projects ELMAX (ANR-20-CE24-0015) and MAGICVALLEY (ANR-18-CE24-0007), and the King Abdullah University of Science and Technology under grant number OSR-2018-CRG7-3717, the DARPA TEE program through Grant MIPR# HR0011831554 from the DOI, European Union’s Horizon 2020 research and innovation Programme under grant agreement 881603 (Graphene Flagship), and the LANEF framework (ANR-10-LABX-51-01) for its support with mutualized infrastructure.

Publisher
Springer Science and Business Media LLC

Journal
npj 2D Materials and Applications

DOI
10.1038/s41699-022-00285-w

arXiv
2106.12808

Additional Links
https://www.nature.com/articles/s41699-022-00285-w

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