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arXiv 2305.03437cond-mat.mes-hall
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范德华异质结构中杂化激子的直接可视化

Direct visualization of hybrid excitons in van der Waals heterostructures

Giuseppe Meneghini, Marcel Reutzel, Stefan Mathias, Samuel Brem, Ermin Malic

AI总结:

本文提出利用tr-ARPES直接观测范德华异质结构中的杂化激子,并预测MoS₂同质双层中会出现由杂化空穴产生的特征性双峰信号,为区分杂化激子与常规激子提供实验方案。

摘要:

范德华异质结构展现出引人入胜的物理现象,包括被束缚的莫尔激子态、反常莫尔激子输运、广义维格纳晶体等。过渡金属二硫化物(TMDs)双层以长寿命、空间分离的层间激子为特征。在强层间隧穿条件下,可以形成由层间激子和层内激子组成的杂化激子态。此时,电子和/或空穴处于两层的叠加态。尽管杂化激子对光学、动力学和输运至关重要,但它们通常在光学上是不活跃的,因此迄今尚未被直接观测到。基于微观且材料特异性的理论,我们表明时间分辨和角分辨光电子能谱(tr-ARPES)是直接可视化这些杂化激子的理想技术。具体而言,我们预测在MoS$_2$同质双层中,杂化空穴会产生特征性的双峰ARPES信号。其相对强度与$Γ$点处两个杂化价带的量子混合比例成正比。由于强杂化,超过0.5 eV的峰间距可以在ARPES实验中被分辨出来。我们的研究为如何直接可视化杂化激子以及如何将其与通常观测到的常规激子特征区分开来提供了具体方案。

英文摘要:

Van der Waals heterostructures show fascinating physics including trapped moire exciton states, anomalous moire exciton transport, generalized Wigner crystals, etc. Bilayers of transition metal dichalcogenides (TMDs) are characterized by long-lived spatially separated interlayer excitons. Provided a strong interlayer tunneling, hybrid exciton states consisting of interlayer and intralayer excitons can be formed. Here, electrons and/or holes are in a superposition of both layers. Although crucial for optics, dynamics, and transport, hybrid excitons are usually optically inactive and have therefore not been directly observed yet. Based on a microscopic and material-specific theory, we show that time- and angle-resolved photoemission spectroscopy (tr-ARPES) is the ideal technique to directly visualize these hybrid excitons. Concretely, we predict a characteristic double-peak ARPES signal arising from the hybridized hole in the MoS$_2$ homobilayer. The relative intensity is proportional to the quantum mixture of the two hybrid valence bands at the $Γ$ point. Due to the strong hybridization, the peak separation of more than 0.5 eV can be resolved in ARPES experiments. Our study provides a concrete recipe of how to directly visualize hybrid excitons and how to distinguish them from the usually observed regular excitonic signatures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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