Electronic and Magnetic Properties of Transition-Metal-Doped WS2 Monolayer; First-Principles Investigations

The electronic structuares and magnetic properties of the transition-metal (TM)-doped WS2 monolayers are investigated by using the first-principles calculations within the density functional theory. The W atoms of the pristine WS2 monolayer are partially replaced by the 3d TMs of Mn, Fe, Co, and Cu with the impurity concentration of about 4%. For the uniformly distributed doping, the ferromagnetic phases are found to be stabilized with the total spin magnetic moments of 1.00, 2.00, 3.00, and 1.00 mu(B) for the Mn-, Fe-, Co-, and Cu-doping, respectively, where not only the spin moments of the TM dopants but also the induced spin moments of the W and S atoms contribute significantly depending on the dopant type as well as on the relaxation. All systems are found to be half-metallic with the spin gap of 0.10-0.53 eV. Among them, the biggest spin gap is found for the doping of Co which is the ingredient of the well-known half-metallic Heusler alloys. When the TM dopants were brought closer keeping the same impurity concentration, the preference of the substitutional doping site and the magnetic phase is changed sensitively depending on the type of doping and the interatomic distance between the TM dopants.