paper

Atomically inspired approach and valley Zeeman effect in transition metal dichalcogenide monolayers

arXiv:1610.02695 · doi:10.1103/PhysRevB.95.155406

Abstract

We developed a six-band model that describes the electronic states of monolayer transition metal dichalcogenides (TMDCs) in -valleys. The set of parameters for the model is uniquely determined by decomposing tight-binding (TB) models in the vicinity of -points. First, we used TB models existing in literature to derive systematic parametrizations for different materials, including MoS, WS, MoSe and WSe. Then, by using the derived six-band Hamiltonian we calculated effective masses, Landau levels, and the effective exciton -factor in different TMDCs. We showed that TB parameterizations existing in literature result in small absolute values of , which are far from the experimentally measured . To further investigate this issue we derived two additional sets of parameters by developing our own TB parameterizations based on simultaneous fitting of ab-initio calculated, within the density functional (DFT) and approaches, energy dispersion and the value of . We showed that the change in TB parameters, which only slightly affects the dispersion of higher conduction and deep valence bands, may result in a significant increase of , yielding close-to-experiment values of . Such a high parameter sensitivity of opens a way to further improvement of DFT and TB models.

9 pages, 4 figures, 5 tables

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