Excitons and trions in monolayer transition metal dichalcogenides: A comparative study between the multiband model and the quadratic single-band model

Abstract

The electronic and structural properties of excitons and trions in monolayer transition metal dichalcogenides are investigated using both a multiband and a single-band model. In the multiband model we construct the excitonic Hamiltonian in the product base of the single-particle states at the conduction and valence band edges. We decouple the corresponding energy eigenvalue equation and solve the resulting differential equation self-consistently, using the finite element method (FEM), to determine the energy eigenvalues and the wave functions. As a comparison, we also consider the simple single-band model which is often used in numerical studies. We solve the energy eigenvalue equation using the FEM as well as with the stochastic variational method (SVM) in which a variational wave function is expanded in a basis of a large number of correlated Gaussians. We find good agreement between the results of both methods, as well as with other theoretical works for excitons, and we also compare with available experimental data. For trions the agreement between both methods is not as good due to our neglect of angular correlations when using the FEM. Finally, when comparing the two models, we see that the presence of the valence bands in the mutiband model leads to differences with the single-band model when (interband) interactions are strong.

14 pages, 11 figures, 3 tables

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Cited by in corpus (10)

• Luminescent emission of excited Rydberg excitons from monolayer WSe2
• Influence of the effective layer thickness on the groundstate and excitonic properties of transition-metal dichalcogenide systems
• Stark shift of excitons and trions in two-dimensional materials
• Theoretical methods for excitonic physics in two-dimensional materials
• A colloquium on the variational method applied to excitons in 2D materials
• Spectrum of exciton states in monolayer transition metal dichalcogenides: angular momentum and Landau levels
• Excited-State Trions in Two Dimensional Materials
• Excitonic theory of doping-dependent optical response in atomically thin semiconductors
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• High-temperature tunable superfluidity of polaritons in Xene monolayers in an optical microcavity