Charge and magnetic states of Mn-, Fe-, and Co-doped monolayer MoS2

First-principles calculations have been performed to investigate the electronic and magnetic properties of monolayer MoS2 substitutionally doped with Mn, Fe, and Co in possible charge states (q). We find that the Mn, Fe, and Co dopants substituting for a Mo atom in monolayer MoS2 (Mn@Mo, Fe@Mo, and Co@Mo) are all magnetic in their neutral and charge states except in the highest positive charge states. Mn@Mo, Fe@Mo, and Co@Mo have the same highest negative charge states of q = -2 for chemical potential of electron just below the conduction band minimum, which corresponds to the electron doping. In the q = -2 state, Mn@Mo has a much larger magnetic moment than its neutral state with the antiferromagnetic coupling between the Mn dopant and its neighboring S atoms maintained, while Fe@Mo and Co@Mo have equal or smaller magnetic moments than their neutral states. The possible charge states of Mn@Mo, Fe@Mo, and Co@Mo and the variation of the magnetic moments for different dopants and charge states are due to the change of the occupation and energy of the anti-bonding defect levels in the band gap. The rich magnetic properties of the neutral and charge states suggest possible realization of the substitutionally Mn-, Fe-, and Co-doped monolayer MoS2 as dilute magnetic semiconductors. (C) 2014 AIP Publishing LLC.