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Updated: Jun 6, 2025

Fabricating van der Waals Heterostructures with Precise Rotational Alignment
Published on: July 5, 2019
Chiral Phonon, Valley Polarization, and Inter/Intravalley Scattering in a van der Waals ReSe2 Semiconductor
Shuai Yang1, Yilun Yu1, Fengrui Sui1
1Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, Shanghai 200241, China.
Abstract:
Exploring valley manipulatable layered semiconductors is highly significant for valleytronic devices. Here, we report the phonon chirality and resulting inter/intravalley scattering in valley polarized van der Waals (vdW) layered ReSe2 by linearly/circularly polarized Raman (L/CPR), transmission (L/CPT), and photoluminescence (L/CPL) spectroscopic techniques. L/CPR combined with scanning transmission electron microscopy determines the Re chains' direction and displays the existence of chiral phonons. The LPT discloses the energetic valley polarization between the Re chains and its perpendicular crystal axis directions. Intriguingly, the valley polarization strength depends on the layer thickness even in a micrometer scale and abnormaly increases with temperature increase. Further, CPT manifests the optical rotation in ReSe2 due to strong chiral phonon-photon coupling. More essentially, L/CPL unveils a strong exciton-like effect (Stokes shift) that can be interpreted from the inter/intravalley scattering related to the (chiral) phonon-carrier coupling. This investigation suggests a promising platform based on a low-symmetry vdW ReSe2 semiconductor for exploring valley physics and fabricating valley(opto)tronic nanodevices.
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