Interfacial engineering of ferromagnetism in wafer-scale van der Waals Fe 4 GeTe 2 far above room temperature.

Despite recent advances in exfoliated vdW ferromagnets, the widespread application of 2D magnetism requires a Curie temperature (T c ) above room temperature as well as a stable and controllable magnetic anisotropy. Here we demonstrate a large-scale iron-based vdW material Fe 4 GeTe 2 with the T c reaching ~530 K. We confirmed the high-temperature ferromagnetism by multiple characterizations. Theoretical calculations suggested that the interface-induced right shift of the localized states for unpaired Fe d electrons is the reason for the enhanced T c , which was confirmed by ultraviolet photoelectron spectroscopy. Moreover, by precisely tailoring Fe concentration we achieved arbitrary control of magnetic anisotropy between out-of-plane and in-plane without inducing any phase disorders. Our finding sheds light on the high potential of Fe 4 GeTe 2 in spintronics, which may open opportunities for room-temperature application of all-vdW spintronic devices.