Efficient valley polarization of charged excitons and resident carriers in Molybdenum disulfide monolayers by optical pumping

Monolayer transition metal dichalcogenides, due to a lack of inversion symmetry and strong spin orbit coupling, exhibit a number of unique features applicable to optical devices. Here, the authors use polarised microphotoluminescence to demonstrate optical pumping of the valley degree of freedom for charge-tunable MoS2 monolayers, the optical features of which they attribute to its unusual band structure.