Electronic and magnetic properties of perfect, vacancy-doped, and nonmetal adsorbed MoSe2, MoTe2 and WS2 monolayers

School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
Physical Chemistry Chemical Physics (Impact Factor: 4.49). 09/2011; 13(34):15546-53. DOI: 10.1039/c1cp21159e
Source: PubMed


Very recently, two-dimensional nanosheets of MoSe(2), MoTe(2) and WS(2) were successfully synthesized experimentally [Science, 2011, 331, 568]. In the present work, the electronic and magnetic properties of perfect, vacancy-doped, and nonmetal element (H, B, C, N, O, and F) adsorbed MoSe(2), MoTe(2) and WS(2) monolayers are systematically investigated by means of first-principles calculations to give a detailed understanding of these materials. It is found that: (1) MoSe(2), MoTe(2) and WS(2) exhibit surprising confinement-induced indirect-direct-gap crossover; (2) among all the neutral native vacancies of MoSe(2), MoTe(2) and WS(2) monolayers, only the Mo vacancy in MoSe(2) can induce spin-polarization and long-range antiferromagnetic coupling; (3) adsorption of nonmetal elements on the surface of MoSe(2), MoTe(2) and WS(2) nanosheets can induce a local magnetic moment; H-absorbed WS(2), MoSe(2), and MoTe(2) monolayers and F-adsorbed WS(2) and MoSe(2) monolayers show long-range antiferromagnetic coupling between local moments even when their distance is as long as ∼12 Å. These findings are a useful addition to the experimental studies of these new synthesized two-dimensional nanosheets, and suggest a new route to facilitate the design of spintronic devices for complementing graphene. Further experimental studies are expected to confirm the attractive predictions.

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    • "Analogously to graphite, the atoms in the layer are bound by strong covalent forces, while van der Waals interactions hold the layers together. In this context, monolayers of MoS 2 and WS 2 have received great attention because they are 2D semiconductor with tunable band gaps depending on size [3] [4] [5]. In particular, exfoliated WS 2 (EWS 2 ) was found to exhibit novel and superior properties with respect to the bulk structure, and hence such a nanomaterial has been used for the fabrication of catalysts [6], lubricants [7], lithium batteries [8], photoconductors [9], probes for scanning probe microscopy [10], shock absorbers [11], solar cell films [12]. "
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    • "Murugan et al. revealed by first-principles calculations that stoichiometric Mo n S2n (n = 1, 2, 5, and 6) and W6S12 clusters as well as several of the nonstoichiometric clusters are magnetic, where the magnetic moments arise due to the partially filled d states [18]. Besides, calculation results indicate that adsorption of nonmetal elements on the surface of WS2 nanosheets can induce a local magnetic moment [19]. In an experimental study, Matte et al. fabricated WS2 nanosheets by hydrothermal method and revealed their ferromagnetism, which was considered to be related to the edges and defects [20]. "
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