Magnitoexcitons in Monolayer Transition-Metal Dichalcogenides

Monolayer transition-metal dichalcogenides (TMDC) such as MoS₂, MoSe₂, WS₂ and Se₂ host a series of exciton Rydberg states denoted by the principal quantum number n = 1, 2, 3, etc. We study the 1s–2s exciton Rydberg states in TMDC monolayers encapsulated by hexagonal boron nitride (hBN) under the action of a magnetic field. The exciton Rydberg states exhibit similar Zeeman shifts but distinct diamagnetic shifts from each other. Excitons in the magnetic field are described in the framework of the potential model. We have used the Keldysh potential to calculate the energies of exciton Rydberg states in hBN-encapsulated monolayers of MoS₂, MoSe₂, WS₂, and WSe₂ under varying magnetic field. Our calculations use as inputs the effective masses of electron and hole obtained in the framework of the density functional theory. The binding energies of exciton are calculated using the first-order perturbation theory, which gives good approximation only in the low magnetic field. These binding energies are comparable to experimental measurements. Our results are consistent with the other theoretical predictions.