AI 中文总结
本文提出考虑二维半导体移动激子离域特性的MDCS微观理论，其计算光谱与掺杂单层MoSe₂实验吻合，揭示激子极化子相互作用依赖相空间填充效应，为MDCS研究提供新见解。
AI 中文摘要
多维相干光谱学（MDCS）超越了标准线性响应探针，是研究激子（束缚电子-空穴对）等准粒子之间关联的有力工具。本文提出一种考虑二维半导体中激子离域特性的MDCS微观理论，与通常用于建模MDCS的现象学少能级方法不同，该理论包含具有连续动量自由度的移动激子。研究发现，与激子动量相关的能量连续体对产生相互作用诱导的退相干，以及捕捉电荷掺杂半导体中不同激子极化子准粒子之间的干涉至关重要。关键的是，本文计算的MDCS光谱与最近关于掺杂单层MoSe₂的实验（Hao等人，《自然·通讯》8，15552（2017））吻合良好，且结果表明激子极化子之间的相互作用强烈依赖于相空间填充效应，其中激子极化子会竞争电子。研究结果表明，微观方法可帮助从二维半导体MDCS的精细结构中获得新见解，也说明微观方法在更广泛地建模MDCS实验方面的实用性。
英文摘要
Multi-dimensional coherent spectroscopy (MDCS) goes beyond standard linear-response probes and provides a powerful tool for investigating correlations between quasiparticles such as excitons (bound electron-hole pairs). Here we present a microscopic theory of MDCS that accounts for the delocalized nature of excitons in two-dimensional semiconductors. In contrast to the more phenomenological few-level approaches typically employed for modelling MDCS, our theory features mobile excitons with continuous momentum degrees of freedom. We find that the energy continuum associated with exciton momenta is crucial for producing interaction-induced decoherence, as well as capturing the interference between different exciton-polaron quasiparticles in the case of charge-doped semiconductors. Crucially, our calculated MDCS spectra agree well with recent experiments on doped monolayer MoSe$_2$ [Hao et al., Nature Communications 8, 15552 (2017)], and they suggest that the interactions between exciton polarons depend strongly on phase-space filling effects, where exciton polarons compete for electrons. Our results demonstrate that microscopic approaches allow one to gain new insights from the fine structure of MDCS on two-dimensional semiconductors, and they illustrate the utility of microscopic approaches to modelling MDCS experiments more generally.
Comments22 pages, 13 figures
