Monolayer Fe3GaX2 (X = I, Br, Sb): High-Temperature Two-Dimensional Magnets and a Novel Partially Ordered Spin State

We systematically investigated the effects of charge doping and strain on monolayer Fe3GaTe2 and proposed three new novel two-dimensional magnetic materials: monolayer Fe3GaX2 (X = I, Br, Sb). We found that both strain and charge doping can tune the magnetic interactions, and tuning by charge doping is more significant. Differential charge analysis revealed that the doped charges predominantly accumulate around the Te atoms. Based on this insight, we introduced Fe3GaI2, Fe3GaBr2, and Fe3GaSb2 monolayers. The Fe3GaI2 and Fe3GaBr2 monolayers contain I and Br atoms rather than Te atoms and emulate an electron-doped Fe3GaTe2 monolayer, resulting in notably high Tc values of 867 and 844 K, respectively. In contrast, the Fe3GaSb2 monolayer mimics a hole-doped Fe3GaTe2 monolayer and presents a mix of ferromagnetic and antiferromagnetic interactions, manifesting a distinctive partially ordered magnetic state. Our study demonstrates that substitution atoms based on the charge-doping effect offer a promising approach for predicting new magnetic materials. The proposed Fe3GaI2, Fe3GaBr2, and Fe3GaSb2 monolayers hold great potential for spintronics applications and may stimulate the pursuit of new types of spin liquid.