Theory of exciton dynamics in time-resolved ARPES: Intra- and intervalley scattering in two-dimensional semiconductors
Theory of exciton dynamics in time-resolved ARPES: Intra- and intervalley scattering in two-dimensional semiconductors
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DOI：
10.1103/physrevb.100.205401
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发表时间：
2019-11-01
影响因子：
3.7
通讯作者：
Knorr, Andreas
中科院分区：
文献类型：
--
作者：
Christiansen, Dominik;Selig, Malte;Knorr, Andreas
时间和角度分辨光电子能谱(TrARPES)是在动量空间直接测量超快电子动力学的一种强有力的光谱方法。然而，具有非常强的库仑相互作用的带隙材料，如单层过渡金属二卤化物，表现出紧密束缚的激子，这决定了它们的光学性质。这就提出了一个问题，激子，特别是激子的形成和驰豫动力学，是否可以在光发射中被检测到。在这里，我们发展了激子时间和角度分辨光电子发射的时间动力学的全微观理论，特别关注了声子介导的光激发激子到动量禁止的暗激子态的热化。我们发现，trarPES能够探测整个布里渊区的超快激子的形成和驰豫。
Time- and angle-resolved photoemission spectroscopy (trARPES) is a powerful spectroscopic method to measure the ultrafast electron dynamics directly in momentum space. However, band gap materials with exceptionally strong Coulomb interaction such as monolayer transition-metal dichalcogenides exhibit tightly bound excitons, which dominate their optical properties. This raises the question of whether excitons, in particular their formation and relaxation dynamics, can be detected in photoemissions. Here, we develop a fully microscopic theory of the temporal dynamics of excitonic time- and angle-resolved photoemission with a particular focus on the phonon-mediated thermalization of optically excited excitons to momentum-forbidden dark exciton states. We find that trARPES is able to probe the ultrafast exciton formation and relaxation throughout the Brillouin zone.