Spin/valley coupled dynamics of electrons and holes at the ${\text{MoS}}_2-{\text{MoSe}}_2$ interface

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 ${\text{MoS}}_2-{\text{MoSe}}_2$ 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, $\sim 30{\text{ns}}^{-1}$ and $<1{\text{ns}}^{-1}$, 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 free carriers unaffected by complex excitonic processes and establishes TMD heterostructures as generators of spin currents in spin/valleytronic devices.

arXiv comment15 + 6 pages; 4 + 3 figures

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Cited by in corpus (4)

• Twist angle dependent interlayer transfer of valley polarization from excitons to free charge carriers in WSe${}_2$/MoSe${}_2$ heterobilayers
• Realization of valley-spin polarized current via parametric pump in monolayer $\mathrm{Mo}{\mathrm{S}}_2$
• Probing the formation of dark interlayer excitons via ultrafast photocurrent
• Light-matter interactions in layered materials and heterostructures: from moiré physics and magneto-optical effects to ultrafast dynamics and hybrid meta-photonics