Spin/Valley Coupled Dynamics of Electrons and Holes at the MoS<sub>2</sub>–MoSe<sub>2</sub> Interface
Abhijeet M. Kumar, Denis Yagodkin, Nele Stetzuhn, Sviatoslav Kovalchuk, Alexey Melnikov, Peter Elliott, S. Sharma, Cornelius Gahl, Kirill I. Bolotin
Abstract
The coupled spin and valley degrees of freedom in transition metal dichalcogenides (TMDs) are considered a promising platform for information processing. Here, we use a TMD heterostructure MoS2–MoSe2 to study optical pumping of spin/valley polarized carriers across the interface and to elucidate the mechanisms governing their subsequent relaxation. By applying time-resolved Kerr and reflectivity spectroscopies, we find that the photoexcited carriers conserve their spin for both tunneling directions across the interface. Following this, we measure dramatically different spin/valley depolarization rates for electrons and holes, ∼30 and <1 ns–1, respectively, and show that this difference relates to the disparity in the spin–orbit splitting in conduction and valence bands of TMDs. Our work provides insights into the spin/valley dynamics of photoexcited carriers unaffected by complex excitonic processes and establishes TMD heterostructures as generators of spin currents in spin/valleytronic devices.