Exciton interaction induced spin splitting in MoS2 monolayer
Abstract
By pumping nonresonantly a MoS2 monolayer at 13 K under a circularly polarized cw laser, we observe exciton energy redshifts that break the degeneracy between B excitons with opposite spin. The energy splitting increases monotonically with the laser power reaching as much as 18 meV, while it diminishes with the temperature. The phenomenon can be explained theoretically by considering simultaneously the bandgap renormalization which gives rise to the redshift and exciton-exciton Coulomb exchange interaction which is responsible for the spin-dependent splitting. Our results offer a simple scheme to control the valley degree of freedom in MoS2 monolayer and provide an accessible method in investigating many-body exciton exciton interaction in such materials.