Spin/Valley Coupled Dynamics of Electrons and Holes at the MoS<sub>2</sub>-MoSe<sub>2</sub> Interface.
basic_science · Level V
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- Record sourced from PubMed, PMID 34410727.
- Also identified by DOI 10.1021/acs.nanolett.1c01538.
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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 MoS<sub>2</sub>-MoSe<sub>2</sub> 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<sup>-1</sup>, 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.