论文标题
在原子较薄的过渡金属二分法中的激子的二维相干光谱的微观多体型理论
Microscopic many-body theory of two-dimensional coherent spectroscopy of excitons and trions in atomically thin transition metal dichalcogenides
论文作者
论文摘要
我们介绍了最近测量的激子二维相干光谱（2DC）的微观多体理论，以及单层Mose $ _ {2} $材料{[} k中的单层trions和Trions。 hao \ textit {et al。}，nano lett。 \ textbf {16}，5109（2016）{]}，在激子密度的稀释极限下，激子和TRIONS可以很好地解释为排斥和有吸引力的极性。我们根据修改后的，依赖时间依赖的极性绿色函数来得出2DCS频谱的简单关系，该函数在单个激子极限中有效。我们的模拟光谱与实验具有极好的定性一致性，而无需引入任何现象学参数，例如破坏率。特别是，实验2DCS光谱中的异分之间的交叉峰之间的量子拍打得到了很好的再现。因此，我们的工作阐明了所观察到的激子曲线相干性光学信号的显微原理。我们发现，理论和实验之间存在两个定量差异：在不同的交叉峰值处，比预期的交叉强度小于预期的交叉强度和稍微不同步的量子beats。暂时，我们将这些残差差异归因于有限的激子密度和由此产生的polaron-polaron相互作用，这在我们的理论中没有考虑到。
We present a microscopic many-body theory of the recently measured two-dimensional coherent spectroscopy (2DCS) of excitons and trions in monolayer MoSe$_{2}$ materials {[}K. Hao \textit{et al.}, Nano Lett. \textbf{16}, 5109 (2016){]}, where excitons and trions can be well interpreted as repulsive and attractive polarons, respectively, in the dilute limit of exciton density. We derive a simple relation for the 2DCS spectrum in terms of a modified, mixing time-dependent polaron Green function, which is valid in the single exciton limit. Our simulated spectra are in excellent qualitative agreement with experiments without introducing any phenomenological parameters such as decoherence rates. In particular, quantum beats between the off-diagonal crosspeaks in the experimental 2DCS spectra are well reproduced. Our work, therefore, clarifies the microscopic principle that underlies the observed optical signals of exciton-trion coherence. We find that there are two quantitative discrepancies between theory and experiment: the smaller than expected crosspeak strength and the slightly unsynchronized quantum beats at different crosspeaks. Tentatively, we attribute these residual discrepancies to the finite exciton density and the resultant polaron-polaron interaction, which is not taken into account in our theory.
