First-principles study on the Janus Monolayer Molybdenum-Sulfur-Selenium

Jun Inagaki^1*, Hung-Chung Hsueh^1,2

¹Department of Physics, Tamkang University, New Taipei City, Taiwan
²X-ray Science Research Center, College of Science, Tamkang University, New Taipei City, Taiwan

* Presenter:Jun Inagaki, email:ctec.inagaki@gmail.com

Few-layered Transition Metal Dichalcogenides (TMDs), such as molybdenum sulfide (MoS2) and molybdenum sellenide (MoSe2), are possessing unique electronic properties. For example, a layer thickness-dependent dimensional crossover of the direct-to-indirect bandgap transition can be attributed to both the significant intra-layer spin-orbital coupling and the lack of inter-layer orbital coupling for the band-edge states at K point. Recently, a novel structure with asymmetry along the out-of-plane direction, so called “Janus” structures, was predicted and successfully synthesized in a monolayer trigonal prism (1H) of TMDs[1]. Such symmetry breaking along the direction perpendicular to the monolayer will induce an intrinic electric field inside the layer and enhance Zeeman-type spin splitting.

In this study, electronic structure of the Janus monolayer molybdenum-sulfur-selenium combinations (MoSSe) are investigated by means of first-principles calculations. Various perturbative corrections to the DFT electronic structure, e.g. GW and spin‐orbit coupling, are performed to calculate the electronic properties of Janus MoSSe.

[1] Hu et al., Phys. Rev. B, 97, 235404 (2018)

Keywords: Janus structure, Spin orbital coupling, GW approximation, Monolayer