Spin splitting and reemergence of charge compensation in monolayer WTe₂ by 3d transition-metal adsorption

The semimetallic WTe₂ has sparked intense interest owing to the non-saturating magnetoresistance, pressure-driven superconductivity and possession of type-II Weyl fermions. The unexpected and fascinating quantum properties are thought to be closely related to its delicate Fermi surface and a special electron-hole-pocket structure. However, in the single-layer limit, the electron-hole-pocket structure is missing owing to the lack of interlayer interaction. Herewith, we demonstrate that 3d transition-metal adsorption is an effective method to modify the electronic properties of monolayer WTe₂ by density functional theory. Spin-splitting and spin-degenerate bands are realized in Ti-, V-, Cr-, Mn-, Fe-, and Co- and Sc-, Ni-, Cu-, and Zn-adsorbed systems, respectively. Especially, the reemergence of the electron-hole pockets appears in the Ni-adsorbed system. The calculated results are robust against inclusion of spin-orbit coupling and Coulomb interaction.