Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS${}_2$ systems

Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS${}_2$ doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,$X$)S${}_2$ ($X=\text{Mn}$, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.

Figure 1

Monolayer MoS${}_2$: (a) Side view, (b) top view with Mo vacancy, (c) spin density for Mn doping with $C_{3v}$ symmetry, and (d) Ni doping with $C_1$ symmetry. Spin densities of $\pm 0.002$$e$/bohr${}^{-3}$ are visualized by red and blue isosurfaces, respectively.

Figure 2

Binding energies of monolayer MoS${}_2$ doped by transition metal atoms from the periods four, five, and six.

Figure 3

DOS of monolayer MoS${}_2$: (a) Pristine, (b) with two S vacancies, (c) with one Mo vacancy, (d) Sc doped, and (e) Mn doped. The energy axis is calibrated with respect to the core states. The dashed vertical lines indicate the Fermi levels.

Figure 4

DOS of (Mo,Ni)S${}_2$ in (a) $C_{3v}$ and (b) $C_1$ symmetry. (c) DOS of (Mo,Zn)S${}_2$ in $C_{3v}$ symmetry.