近日，美国得克萨斯大学奥斯汀分校Xiaoqin Li团队研究了十二角半导体准晶体中的场可调谐谷耦合。2025年11月11日，《自然—物理学》杂志发表了这一成果。
准晶的特征在于其原子排列具有长程有序但无周期性。范德瓦尔斯双层结构为可控调节两层间的原子对齐方式提供了可能，可从周期性的莫尔条纹晶体变化到非周期性的准晶。
研究组发现，在十二重对称的WSe2准晶中，通过高阶Umklapp散射作用，两层中原本分离的谷在动量空间中被任意拉近。随后施加一个适度的垂直电场即可诱导强烈的层间谷杂化，表现为另一个杂化激子双重态。同时，研究组观察到低电场下存在的三元子（trion）消失，他们认为这是由于准晶势场导致波函数的空间分布发生改变所致。这可能是局域化的前兆。该研究突显了非公度体系将任意动量对拉近的能力，从而为谷工程提供了新的机遇。
附：英文原文
Title: Field-tunable valley coupling in a dodecagonal semiconductor quasicrystal
Author: Liu, Zhida, Gao, Qiang, Li, Yanxing, Espitia, Giovanny, Liu, Xiaohui, Shi, Chuqiao, Zhang, Fan, Kim, Dong Seob, Ni, Yue, Mackenzie, Miles, Abudayyeh, Hamza, Watanabe, Kenji, Taniguchi, Takashi, Han, Yimo, Naik, Mit H., Shih, Chih-Kang, Khalaf, Eslam, Li, Xiaoqin
Issue&Volume: 2025-11-11
Abstract: Quasicrystals are characterized by atomic arrangements having long-range order without periodicity. Van der Waals bilayers provide an opportunity to controllably vary the atomic alignment between two layers from a periodic moiré crystal to an aperiodic quasicrystal. Here we reveal that in a dodecagonal WSe2 quasicrystal, two separate valleys in separate layers are brought arbitrarily close in momentum space through higher-order Umklapp scatterings. A modest perpendicular electric field is then sufficient to induce strong interlayer valley hybridization, manifested as another hybrid excitonic doublet. Concurrently, we observe the disappearance of the trion that exists at low field, which we attribute to a modified spatial distribution of the wavefunction due to the quasicrystal potential. This is possibly a precursor to localization. Our findings highlight the ability of incommensurate systems to bring any pair of momenta into close proximity, thereby introducing opportunities for valley engineering.
DOI: 10.1038/s41567-025-03080-8
Source: https://www.nature.com/articles/s41567-025-03080-8