Quasicrystals are characterized by atomic arrangements possessing long-range order without periodicity. Van der Waals (vdW) bilayers provide a unique opportunity to controllably vary atomic alignment between two layers from a periodic moir\'e crystal to an aperiodic quasicrystal. Here, we reveal a remarkable consequence of the unique atomic arrangement in a dodecagonal WSe2 quasicrystal: the K and Q valleys in separate layers are brought arbitrarily close in momentum space via higher-order Umklapp scatterings. A modest perpendicular electric field is sufficient to induce strong interlayer K-Q hybridization, manifested as a new hybrid excitonic doublet. Concurrently, we observe the disappearance of the trion resonance and attribute it to quasicrystal potential driven localization. Our findings highlight the remarkable attribute of incommensurate systems to bring any pair of momenta into close proximity, thereby introducing a novel aspect to valley engineering.
@article{arxiv.2408.02176,
title = {Field-Tunable Valley Coupling and Localization in a Dodecagonal Semiconductor Quasicrystal},
author = {Zhida Liu and Qiang Gao and Yanxing Li and Xiaohui Liu and Fan Zhang and Dong Seob Kim and Yue Ni and Miles Mackenzie and Hamza Abudayyeh and Kenji Watanabe and Takashi Taniguchi and Chih-Kang Shih and Eslam Khalaf and Xiaoqin Li},
journal= {arXiv preprint arXiv:2408.02176},
year = {2024}
}