文章基本信息

标题：Thickness dependence of spin polarization and electronic structure of ultra-thin films of MoS₂ and related transition-metal dichalcogenides
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作者：Tay-Rong Chang ; Hsin Lin ; Horng-Tay Jeng 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2014
卷号：4
DOI：10.1038/srep06270
出版社：Springer Nature
摘要：We have carried out thickness dependent first-principles electronic structure calculations on ultra-thin films of transition-metal dichalcogenides MX₂ (M = Mo or W; X = S, Se, or Te). When spin-orbit coupling (SOC) is included in the computations, monolayer MX₂ thin films display spin-split states around the valence band maximum at the Brillouin zone corners with nearly 100% spin polarization. The spins are aligned oppositely along out-of-the-plane direction at the K and K′ points. For the bilayer films, spin polarization of this SOC induced band splitting can be switched on or off by an out-of-the-plane external electric field. The spin-polarized states are weakly coupled between the layers in bulk MX₂ compounds with small k_z dispersion. We confirm a transition from an indirect to direct band gap as the thickness is reduced to a monolayer in MoS₂, in agreement with recent experimental findings. Owing to the presence of a large spin-splitting energy and an insulating band gap, MX₂ compounds have great potential for spin/valley electronic applications at room temperature.