Spin splitting in a MoS2 monolayer induced by exciton interaction

Yao Li, Guangyao Li, Xiaokun Zhai, Shifu Xiong, Hongjun Liu, Xiao Wang, Haitao Chen, Ying Gao, Xiu Zhang, Tong Liu, Yuan Ren, Xuekai Ma, Hongbing Fu, Tingge Gao

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By pumping nonresonantly a MoS2 monolayer at 13 K under a circularly polarized continuous wave (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, and it diminishes with the increase of temperature. The phenomenon can be explained theoretically by considering simultaneously the band-gap renormalization that gives rise to the redshift and exciton-exciton Coulomb exchange interaction that is responsible for the spin-dependent splitting. Our results offer a simple scheme to control the valley degree of freedom for MoS2 monolayers and provide an accessible method in investigating the many-body exciton-exciton interaction in such materials.
Original languageEnglish
Number of pages6
JournalPhysical Review B
Issue number24
Publication statusPublished - 25 Jun 2020

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