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 and 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 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 crystal thickness decreases from bulk to a monolayer. Using kp calculations, we demonstrate that the observed dependence of g -factors for different materials is well accounted for by hybridization of electronic states in the and valleys. The mixing of the valence and conduction band states induced by the interlayer interaction decreases the g -factor with increasing layer number. The effect is the largest for MoTe ₂ , followed by MoSe ₂ , and the smallest for WSe ₂ .