Probing mesoscopic nonlocal screening in van der Waals heterostructures with polaritons
Abstract
Predictive optical modelling of van der Waals (vdW) heterostructures is critical for meta-optics, near-field photonics and quantum technologies. At their buried interfaces, charge transfer and spatially extended screening challenge local descriptions based on layer-by-layer stacking of fixed permittivity tensors. However, such nonlocal corrections have been established mainly for plasmonic systems at {\aa}ngstr\"om-nanometre scales and are often assumed negligible on optical-wavelength scales. Here we challenge this view by uncovering a mesoscopic nonlocal screening regime, extending up to ~140 nm, at buried charge-transfer interfaces in transition-metal dichalcogenide/{\alpha}-molybdenum trioxide (TMDC/{\alpha}-MoO3) phonon-polaritonic heterostructures. Using phonon polaritons as an ultrasensitive probe, we quantify charge transfer from polariton-wavelength shifts and find a thickness-independent saturated response as {\alpha}-MoO3 is thinned. Rather than merely complicating optical modelling, this nonlocal saturation turns a design-level correction into an opportunity by yielding a transferable cross-material metric. Across more than 120 devices, this metric scales linearly with the work-function difference between the TMDC and {\alpha}-MoO3. We further identify a lattice-mismatch-set energy threshold for charge transfer, revising Anderson-type band alignment for vdW interfaces.
Keywords
Cite
@article{arxiv.2603.09383,
title = {Probing mesoscopic nonlocal screening in van der Waals heterostructures with polaritons},
author = {Xuezhi Ma and Zhipeng Li and Ruihuan Duan and Zeyu Deng and Hao Hu and Mengting Jiang and Yueqian Zhang and Xiaoyuan He and Qiushi Liu and Qiyao Liu and Yuan Ma and Fengxia Wei and Jiayu Shi and Chunqi Zheng and Guangwei Hu and Ping Koy Lam and Chengwei Qiu and Yu Luo and Zheng Liu and Qian Wang},
journal= {arXiv preprint arXiv:2603.09383},
year = {2026}
}