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.

arXiv comment14 pages, 11 figures, 3 tables

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• The Coulomb interaction in monolayer transition-metal dichalcogenides
• Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
• Interlayer excitons in transition metal dichalcogenide heterostructures
• The valley Zeeman effect in inter- and intra-valley trions in monolayer WSe${}_2$
• Luminescent emission of excited Rydberg excitons from monolayer WSe2
• Marrying excitons and plasmons in monolayer transition-metal dichalcogenides
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• Influence of the effective layer thickness on the groundstate and excitonic properties of transition-metal dichalcogenide systems
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• Few-body systems in condensed matter physics
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• Exciton oscillator strength in two-dimensional Dirac materials
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