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-FeCl2, FeBr2, VCl2, and VBr2) by reduction of their trihalide counterparts is developed. Representatively, ultrathin (similar to 8.6 nm) FeCl2 flakes are synthesized on SiO2/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 FeCl2 with a Neel temperature at similar to 17 K. Scanning tunneling microscopy and spectroscopy further identify the atomic-scale structures and band features of 1L and bilayer FeCl2 on graphene/Cu foil.

Automated summary

Two-dimensional transition metal dihalides (TMDHs) have attracted extensive attention for their diverse magnetic properties and potential applications in spintronics. However, the controlled growth of 2D TMDHs is challenging due to their sensitivity to atmospheric moisture. In this study, a universal chemical vapor deposition synthesis route for high-quality 2D TMDH flakes (1T-FeCl2, FeBr2, VCl2, and VBr2) is developed using a nitrogen-filled glovebox system. The synthesized FeCl2 flakes exhibit interlayer antiferromagnetic ordering with a Neel temperature of approximately 17 K.