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

Wang, Hangtian; Lu, Haichang; Guo, Zongxia; Li, Ang; Wu, Peichen; Li, Jing; Xie, Weiran; Sun, Zhimei et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Despite recent advances in exfoliated vdW ferromagnets, the widespread application of 2D magnetism requires a Curie temperature (T<sub>c</sub>) above room temperature as well as a stable and controllable magnetic anisotropy. Here we demonstrate a large-scale iron-based vdW material Fe<sub>4</sub>GeTe<sub>2</sub> with the T<sub>c</sub> 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<sub>c</sub>, 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<sub>4</sub>GeTe<sub>2</sub> in spintronics, which may open opportunities for room-temperature application of all-vdW spintronic devices.