十二重对称半导体准晶体中的场可调能谷耦合与局域化
Field-Tunable Valley Coupling and Localization in a Dodecagonal Semiconductor Quasicrystal
AI总结：
本研究在十二重对称 WSe2 vdW 准晶体中证明，高阶 Umklapp 散射可使层间 K、Q 能谷在动量上任意接近，垂直电场可调控其杂化并导致局域化。
摘要：
准晶体的特征在于原子排列具有长程有序但不具备周期性。Van der Waals（vdW）双层结构提供了一个独特机会，可可控地改变两层之间的原子对准，使其从周期性莫尔晶体转变为非周期性准晶体。在这里，我们揭示了十二重对称 WSe2 准晶体中独特原子排列带来的显著结果：通过高阶 Umklapp 散射，位于不同层中的 K 能谷和 Q 能谷在动量空间中可被拉近至任意接近的程度。一个适度的垂直电场便足以引发强烈的层间 K-Q 杂化，并表现为新的杂化激子双峰。与此同时，我们观察到 trion 共振消失，并将其归因于准晶体势驱动的局域化。我们的发现突显了非公度体系能够将任意一对动量拉近的显著特性，从而为能谷工程引入了一个新的方面。
英文摘要：
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 moiré 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.
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