2026, Twist-programmable Exciton Polarization through Dual Anisotropic Proximity in CrOCl/WSe₂/CrOCl heterostructures, ACS Photonics.

Abstract:

Polarization control in atomically thin semiconductors enables optical information to be encoded beyond intensity and energy. In group-VI transition metal dichalcogenides (TMDs), however, the high in-plane lattice symmetry suppresses excitonic linear polarization, and symmetry breaking from a single van der Waals interface typically provides only weak, weakly programmable anisotropy. Here we create a dual-interface anisotropic proximity platform by sandwiching monolayer WSe₂ between two low-symmetry antiferromagnetic CrOCl crystals with controlled relative orientation. When the CrOCl crystallographic axes are nearly aligned, the two interfaces act cooperatively and enhance the degree of linear polarization of WSe₂ excitons by a factor of 4-6 relative to single-interface structures. Rotating the CrOCl axes drives a continuous evolution from constructive enhancement to near cancellation, following a cosine-like dependence captured by a Stokes-vector superposition model. An out-of-plane magnetic field further reconfigures the anisotropy through the antiferromagnetic-to-ferrimagnetic transition of CrOCl, yielding a nonmonotonic polarization response. First-principles calculations show that the dual interface strengthens charge redistribution and amplifies W-Se bond distortion by approximately threefold. These results establish multi-interface anisotropy engineering as a programmable strategy for controlling exciton polarization in van der Waals semiconductors.

Keywords: Exciton polarization, van der Waals heterostructures, dual-interface anisotropic, CrOCl, WSe₂.

Link: https://pubs.acs.org/a/5449629?guestAccessKey=d11cb3df-2624-473e-bc76-ad6852607809

acsphotonics.6c01717(15).pdf