AI Article Synopsis
- The study investigates excitons in 2H-WSe_{2} using advanced spectroscopic techniques, focusing on how these excitons can be manipulated through the use of circularly polarized light.
- The XUV photoemission method allows researchers to specifically measure the spin polarization of both bright and dark excitons at the surface level, revealing a difference in their behaviors.
- Findings indicate that while bright excitons' spin polarization diminishes due to scattering, dark excitons may serve as a resource for local spin polarization, potentially benefiting spin injection in layered materials.
Article Abstract
We performed spin-, time- and angle-resolved extreme ultraviolet photoemission spectroscopy of excitons prepared by photoexcitation of inversion-symmetric 2H-WSe_{2} with circularly polarized light. The very short probing depth of XUV photoemission permits selective measurement of photoelectrons originating from the top-most WSe_{2} layer, allowing for direct measurement of hidden spin polarization of bright and momentum-forbidden dark excitons. Our results reveal efficient chiroptical control of bright excitons' hidden spin polarization. Following optical photoexcitation, intervalley scattering between nonequivalent K-K^{'} valleys leads to a decay of bright excitons' hidden spin polarization. Conversely, the ultrafast formation of momentum-forbidden dark excitons acts as a local spin polarization reservoir, which could be used for spin injection in van der Waals heterostructures involving multilayer transition metal dichalcogenides.
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| http://dx.doi.org/10.1103/PhysRevLett.131.066402 | DOI Listing |
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