标题： 在电荷可调的单层 WSe$_2$中的十谷激子复合体 显示英文标题

标题： Ten-valley excitonic complexes in charge-tunable monolayer WSe$_2$

摘要： 二维（2D）半导体如单层WSe$_2$的光学响应由激子主导。增强的相互作用导致形成多体激子复合物，这为激子和量子多体理论提供了测试平台。特别是，相关的多体激子复合物可能构成一个极限情况，对竞争的激子描述进行测试。在这里，我们报告了一种此前未观察到的多体激子复合物，该复合物在静电掺杂$K$和$Q$谷时出现。我们使用具有异常薄栅介质的电荷可调器件，对WSe$_2$激子景观进行了光学探测，这种介质可以实现高达几$10^{13}$cm$^{-2}$的掺杂。在这个以前未探索的范围内，我们在存在多达10个填充谷的情况下观察到了热力学稳定态的出现。我们通过磁光测量了解了这种复杂物理的机制。我们的结果可以用一个模型来很好地描述，该模型中形成的激子复合物的行为取决于光激发电子-空穴对相互作用的可区分费米海的数量。除了扩展二维半导体中激子的种类外，这种极端复杂的特性可能能够探测激子模型的极限，并有助于回答关于低维半导体中屏蔽库仑相互作用的开放性问题。 显示英文摘要

摘要： The optical response of two-dimensional (2D) semiconductors such as monolayer WSe$_2$ is dominated by excitons. Enhanced interactions result in the formation of many-body excitonic complexes, which provide a testing ground for excitons and quantum many-body theories. In particular, correlated many-body excitonic complexes could constitute a limiting case that puts competing exciton descriptions to the test. Here, we report a hitherto unobserved many-body excitonic complex that emerges upon electrostatically doping both the $K$ and $Q$ valleys with charge carriers. We optically probe the WSe$_2$ exciton landscape using charge-tunable devices with unusually thin gate dielectrics that facilitate doping up to several $10^{13}$ cm$^{-2}$. In this previously unexplored regime, we observe the emergence of the thermodynamically stable state in the presence of as many as 10 filled valleys. We gain insight into the physics of this complex using magneto-optical measurements. Our results are well-described by a model where the behavior of the formed exciton complex depends on the number of distinguishable Fermi seas with which the photoexcited electron-hole pair interacts. In addition to expanding the repertoire of excitons in 2D semiconductors, the extremal nature of this complex could probe the limit of exciton models and could help answer open questions about the screened Coulomb interaction in low-dimensional semiconductors.