Above-Room-Temperature Ferromagnetism in Large-Scale Epitaxial Fe3GaTe2/Graphene van der Waals Heterostructures.

Abstract

Fe₃GaTe₂ (FGaT), a two-dimensional (2D) layered ferromagnetic metal, exhibits a high Curie temperature (T_C) of ∼360 K along with strong perpendicular magnetic anisotropy (PMA), making it a promising material candidate for next-generation energy-efficient magnetic devices. However, the vast majority of studies on FGaT to date have been limited to millimeter-sized bulk crystals and exfoliated flakes, which are unsuitable for practical applications and integration into device processing. Also, its combination with other 2D materials to form van der Waals (vdW) heterostructures has only been achieved by flake stacking. Consequently, the controlled large-area growth of FGaT and related heterostructures remains largely unexplored. In this work, we demonstrate the high-quality, large-area growth of epitaxial FGaT thin films on single-crystalline graphene/SiC templates using molecular beam epitaxy. Structural characterization confirms the high crystalline quality of the continuous FGaT/graphene vdW heterostructures. Temperature-dependent magnetization and anomalous Hall measurements reveal robust PMA with an enhanced T_C well above room temperature, reaching up to 400 K. Furthermore, X-ray absorption and X-ray magnetic circular dichroism spectra provide insight into the spin and orbital magnetic moment contributions, further validating the high T_C and robust PMA. These findings are highly significant for the future development of high-performance spintronic devices based on 2D heterostructures, with potential applications in next-generation data storage, logic processing, and quantum technologies.