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, ∼30ns−1 and <1ns−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 free carriers unaffected by complex excitonic processes and establishes TMD heterostructures as generators of spin currents in spin/valleytronic devices.
@article{arxiv.2103.09934,
title = {Spin/valley coupled dynamics of electrons and holes at the ${\text{MoS}_{2}-\text{MoSe}_{2}}$ interface},
author = {Abhijeet Kumar and Denis Yagodkin and Nele Stetzuhn and Sviatoslav Kovalchuk and Alexey Melnikov and Peter Elliott and Sangeeta Sharma and Cornelius Gahl and Kirill I. Bolotin},
journal= {arXiv preprint arXiv:2103.09934},
year = {2021}
}