Prediction of a new two-dimensional valleytronic semiconductor MoGe₂P₄ with large valley spin splitting

Recently, MoSi₂N₄ with large valley spin splitting was experimentally synthesized. However, materials with large valley spin splitting are still rare. We predict a new two-dimensional (2D) MoGe₂P₄ material. It has large valley spin splitting and excellent optical absorption properties. The results show that 2D MoGe₂P₄ is a direct semiconductor with a bandgap of 887 meV. Its valley spin splitting (ΔV) at the top of the valence band is 153 meV because of the inversion symmetry breaking and spin-orbit coupling (SOC). 2D MoGe₂P₄ transforms from a semiconductor to a metal under a biaxial strain of 6%. ΔV increases monotonically from 137 meV to 157 meV under biaxial strain. In addition, the lowest exciton state of 2D MoGe₂P₄ is near 770 nm, and the optical absorption coefficient in the ultraviolet range is higher than that of MoS₂. Our results suggest that 2D MoGe₂P₄ has excellent potential for applications in valley electronics and optoelectronic devices.