Strong intrinsic room-temperature ferromagnetism in freestanding non-van der Waals ultrathin 2D crystals

Control of ferromagnetism is of critical importance for a variety of proposed spintronic and topological quantum technologies. Inducing long-range ferromagnetic order in ultrathin 2D crystals will provide more functional possibility to combine their unique electronic, optical and mechanical properties to develop new multifunctional coupled applications. Recently discovered intrinsic 2D ferromagnetic crystals such as Cr2Ge2Te6, CrI3 and Fe3GeTe2 are intrinsically ferromagnetic only below room temperature, mostly far below room temperature (Curie temperature, similar to 20-207 K). Here we develop a scalable method to prepare freestanding non-van der Waals ultrathin 2D crystals down to mono- and few unit cells (UC) and report unexpected strong, intrinsic, ambient-air-robust, room-temperature ferromagnetism with T-C up to similar to 367 K in freestanding non-van der Waals 2D CrTe crystals. Freestanding 2D CrTe crystals show comparable or better ferromagnetic properties to widely-used Fe, Co, Ni and BaFe12O19, promising as new platforms for room-temperature intrinsically-ferromagnetic 2D crystals and integrated 2D devices.

Automated summary

A scalable method has been developed to prepare freestanding non-van der Waals ultrathin 2D crystals, leading to the discovery of strong, ambient-air-robust room-temperature ferromagnetism in freestanding non-van der Waals 2D CrTe crystals. These freestanding 2D CrTe crystals show comparable or even better ferromagnetic properties than commonly used Fe, Co, Ni, and BaFe12O19, making them promising as new platforms for intrinsically ferromagnetic 2D crystals at room temperature and integrated 2D devices.