Two-dimensional ferromagnetic semiconductor monolayers TbXH (X=Br,Cl,I): Results of first-principles calculations

The current primary challenge in valley electronics research is to achieve large-scale spontaneous valley polarization. In this paper, using first-principles calculations, we predict a promising class of two-dimensional ferromagnetic semiconductors, namely Janus $\mathrm{Tb}X\mathrm{H}$ $(X=\text{Br},\mathrm{Cl},\mathrm{I})$ monolayers. Our first-principles calculations reveal that these materials can achieve a valley polarization of up to 112 meV due to ferromagnetic exchange and spin-orbit coupling effects. Additionally, we explored how biaxial strain affects their magnetic anisotropy energy and valley polarization. These results highlight the crucial role of strain in modulating spin and valley properties while also opening different avenues for utilizing ferromagnetic semiconductor materials in spintronics and valleytronics applications.