Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2
Mário Ribeiro, Giulio Gentile, A. Marty, Djordje Došenović, Hanako Okuno, Céline Vergnaud, Jean‐François Jacquot, D. Jalabert, Danilo Longo, Philippe Ohresser, Ali Hallal, Mairbek Chshiev, Olivier Boulle, Frédéric Bonell, Matthieu Jamet
Abstract
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 Fe 5 GeTe 2 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 Fe 5 GeTe 2 , 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.