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

D. V Rybkovskiy (1) , I.C. Gerber (2) , M. V Durnev (3)

1 GPI - A. M. Prokhorov General Physics Institute
2 LPCNO - Laboratoire de physique et chimie des nano-objets
3 A.F. Ioffe Physical-Technical Institute

We developed a six-band k · p model that describes the electronic states of monolayer transition metal dichalcogenides (TMDCs) in K-valleys. The set of parameters for the k · p model is uniquely determined by decomposing tight-binding (TB) models in the vicinity of K ±-points. First, we used TB models existing in literature to derive systematic parametrizations for different materials, including MoS2, WS2, MoSe2 and WSe2. Then, by using the derived six-band k · p Hamiltonian we calculated effective masses, Landau levels, and the effective exciton g-factor g X 0 in different TMDCs. We showed that TB parameterizations existing in literature result in small absolute values of g X 0 , which are far from the experimentally measured g X 0 ≈ −4. To further investigate this issue we derived two additional sets of k · p parameters by developing our own TB parameterizations based on simultaneous fitting of ab-initio calculated, within the density functional (DFT) and GW approaches, energy dispersion and the value of g X 0. 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 |g X 0 |, yielding close-to-experiment values of g X 0. Such a high parameter sensitivity of g X 0 opens a way to further improvement of DFT and TB models.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

D. V Rybkovskiy, I.C. Gerber, M. V Durnev. Atomically inspired k · p approach and valley Zeeman effect in transition metal dichalcogenide monolayers. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2017, 95 (15), pp.155406. ⟨10.1103/PhysRevB.95.155406⟩. ⟨hal-01868514⟩