Thickness dependence of spin polarization and electronic structure of ultra-thin films of MoS2 and related transition-metal dichalcogenides

Tay Rong Chang, Hsin Lin, Horng Tay Jeng, A. Bansil

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23 Citations (Scopus)

Abstract

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 kz 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.

Original languageEnglish
Article number6270
JournalScientific reports
Volume4
DOIs
Publication statusPublished - 2014 Sep 5

All Science Journal Classification (ASJC) codes

  • General

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