Zeeman spectroscopy of excitons and hybridization of electronic states in few-layer WSe${}_2$, MoSe${}_2$ and MoTe${}_2$

Abstract

Monolayers and multilayers of semiconducting transition metal dichalcogenides (TMDCs) offer an ideal platform to explore valley-selective physics with promising applications in valleytronics and information processing. Here we manipulate the energetic degeneracy of the ${\mathrm{K}}^{+}$ and ${\mathrm{K}}^{-}$ valleys in few-layer TMDCs. We perform high-field magneto-reflectance spectroscopy on WSe${}_2$, MoSe${}_2$, and MoTe${}_2$ crystals of thickness from monolayer to the bulk limit under magnetic fields up to 30 T applied perpendicular to the sample plane. Because of a strong spin-layer locking, the ground state A excitons exhibit a monolayer-like valley Zeeman splitting with a negative $g$-factor, whose magnitude increases monotonically when thinning the crystal down from bulk to a monolayer. Using the $\mathbf{k}\cdot \mathbf{p}$ calculation, we demonstrate that the observed evolution of $g$-factors for different materials is well accounted for by hybridization of electronic states in the ${\mathrm{K}}^{+}$ and ${\mathrm{K}}^{-}$ valleys. The mixing of the valence and conduction band states induced by the interlayer interaction decreases the $g$-factor magnitude with an increasing layer number. The effect is the largest for MoTe${}_2$, followed by MoSe${}_2$, and smallest for WSe${}_2$. Keywords: MoSe${}_2$, WSe${}_2$, MoTe${}_2$, valley Zeeman splitting, transition metal dichalcogenides, excitons, magneto optics.

arXiv comment14 pages, 5 figures

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• Exciton g-factors in monolayer and bilayer WSe${}_2$ from experiment and theory
• Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
• Charge transfer and asymmetric coupling of MoSe${}_2$ valleys to the magnetic order of CrSBr
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• Magnetoexcitons in transition-metal dichalcogenides monolayers, bilayers, and van der Waals heterostructures
• Ultrafast pseudospin quantum beats in multilayer WSe${}_2$ and MoSe${}_2$
• Theory of the Coherent Response of Magneto-Excitons and Magneto-Biexcitons in Monolayer Transition Metal Dichalcogenides
• High-performance broadband Faraday rotation spectroscopy of 2D materials and thin magnetic films
• Analogy and dissimilarity of excitons in monolayer and bilayer of MoSe${}_2$
• Adsorption and dissociation of diatomic molecules in monolayer $1H$-MoSe${}_2$
• Valley pseudospin relaxation of charged excitons in monolayer MoTe${}_2$
• Rydberg series of intralayer K-excitons in WSe${}_2$ multilayers