Charged exctions in two-dimensional transition-metal dichalcogenides - semiclassical calculation of Berry-curvature effects

Abstract

We theoretically study the role of the Berry curvature on neutral and charged excitons in two-dimensional transition-metal dichalcogenides. The Berry curvature arises due to a strong coupling between the conduction and valence bands in these materials that can to great extent be described within the model of massive Dirac fermions. The Berry curvature lifts the degeneracy of exciton states with opposite angular momentum. Using an electronic interaction that accounts for non-local screening effects, we find a Berry-curvature induced splitting of $\sim 17$ meV between the 2$p_{-}$ and 2$p_{+}$ exciton states in WS${}_2$, consistent with experimental findings. Furthermore, we calculate the trion binding energies in WS${}_2$ and WSe${}_2$ for a large variety of screening lenghts and different dielectric constants for the environment. Our approach indicates the prominent role played by the Berry curvature along with non-local electronic interactions in the understanding of the energy spectra of neutral and charged excitons in transition-metal dichalcogenides and in the the interpretation of their optical properties.

arXiv comment11 pages, 3 figures

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Cited by in corpus (9)

• Band nesting and exciton spectrum in monolayer MoS${}_2$
• Exciton oscillator strength in two-dimensional Dirac materials
• Anomalous exciton transport in response to a uniform, in-plane electric field
• Variationally optimized orbital approach to trions in two-dimensional materials
• Quantum Geometric Exciton Drift Velocity
• Role of the Berry curvature on BCS-type superconductivity in two-dimensional materials
• Inheritance of the exciton geometric structure from Bloch electrons in two-dimensional layered semiconductors
• Quantum Internal Structure of Plasmons
• Normal state quantum geometry, non-locality and superconductivity