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<p>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 WSe<sub>2</sub> 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.</p>

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Field-tunable valley coupling in a dodecagonal semiconductor quasicrystal

  • 期刊论文

  • 发表日期：

    2025年11月11日

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  • Zhida Liu,
  • Qiang Gao,
  • Yanxing Li,
  • Giovanny Espitia,
  • Xiaohui Liu,
  • Chuqiao Shi,
  • Fan Zhang,
  • Dong Seob Kim,
  • Yue Ni,
  • Miles Mackenzie,
  • Hamza Abudayyeh,
  • Kenji Watanabe,
  • Takashi Taniguchi,
  • Yimo Han,
  • Mit H. Naik,
  • Chih-Kang Shih,
  • Eslam Khalaf,
  • Xiaoqin Li

摘要

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.