General Synthesis of 2D Magnetic Transition Metal Dihalides via Trihalide Reduction.

Two-dimensional (2D) transition metal dihalides (TMDHs) have been receiving extensive attention due to their diversified magnetic properties and promising applications in spintronics. However, controlled growth of 2D TMDHs remains challenging owing to their extreme sensitivity to atmospheric moisture. Herein, using a home-built nitrogen-filled interconnected glovebox system, a universal chemical vapor deposition synthesis route of high-quality 2D TMDH flakes (1T-FeCl 2 , FeBr 2 , VCl 2 , and VBr 2 ) by reduction of their trihalide counterparts is developed. Representatively, ultrathin (∼8.6 nm) FeCl 2 flakes are synthesized on SiO 2 /Si, while on graphene/Cu foil the thickness can be down to monolayer (1L). Reflective magnetic circular dichroism spectroscopy shows an interlayer antiferromagnetic ordering of FeCl 2 with a Neel temperature at ∼17 K. Scanning tunneling microscopy and spectroscopy further identify the atomic-scale structures and band features of 1L and bilayer FeCl 2 on graphene/Cu foil.