First-principle study of single TM atoms X (X=Fe, Ru or Os) doped monolayer WS_2 systems

摘要

We report the structural, magnetic and electronic properties of the pristine and single TM atoms X (X = Fe, Ru or Os) doped monolayer WS2 systems based on first-principle calculations. The results show that the W-S bond shows a stronger covalent bond, but the covalency is obviously weakened after the substitution of W atom with single X atoms, especially for Ru (4d(7)5s(1)) with the easily lost electronic configuration. The smaller total energies of the doped systems reveal that the spin-polarized states are energetically favorable than the non-spin-polarized states, and the smallest total energy of -373.918 eV shows the spin-polarized state of the Os doped monolayer WS2 system is most stable among three doped systems. In addition, although the pristine monolayer WS2 system is a nonmagnetic-semiconductor with a direct band gap of 1.813 eV, single TM atoms Fe and Ru doped monolayer WS2 systems transfer to magnetic-HM with the total moments Mtot of 1.993 and 1.962 mu(B), while single TM atom Os doped monolayer WS2 systems changes to magnetic-metal with the total moments Mfot of 1.569 MB. Moreover, the impurity states with a positive spin splitting energies of 0.543, 0.276 and 0.1999 eV near the Fermi level Er are mainly contributed by X - d(xy) and X - dx(2) y(2) states hybridized with its nearest neighbor atom W - d(z2) states for Fe, Ru and Os doped monolayer WS2 system, respectively. Finally, we hope that the present study on monolayer WS2 will provide a useful theoretical guideline for exploring low-dimensional spintronic materials in future experiments. (C) 2018 Elsevier Ltd. All rights reserved.