Valley dynamics of excitons in monolayer dichalcogenides
Valley dynamics of excitons in monolayer dichalcogenides
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DOI：
10.1002/pssr.201700131
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发表时间：
2017-05
期刊：
影响因子：
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通讯作者：
G. Plechinger;P. Nagler;A. Arora;R. Schmidt;A. Chernikov;J. Lupton;R. Bratschitsch;C. Schüller
中科院分区：
文献类型：
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作者：
G. Plechinger;P. Nagler;A. Arora;R. Schmidt;A. Chernikov;J. Lupton;R. Bratschitsch;C. Schüller
单层过渡金属二卤化物(TMDCs)最近成为电子应用的可能候选者，因为自旋和谷假自旋直接耦合并通过大的自旋分裂而稳定。在这些半导体材料中，光激发的电子-空穴对形成紧密的库仑束缚激子，具有大的结合能。激子跃迁的选择规则允许利用共振激发直接光学产生谷极化激子群。在这里，我们用时间分辨克尔旋转的方法研究了三种不同的TMDDC在低温下单分子膜中的激子谷动力学。我们观察到钨基和钼基TMDDC的山谷动力学有明显的不同，这与这些材料中导带自旋分裂的相反顺序直接相关。
Monolayer transition‐metal dichalcogenides (TMDCs) have recently emerged as possible candidates for valleytronic applications, as the spin and valley pseudospin are directly coupled and stabilized by a large spin splitting. In these semiconducting materials, optically excited electron–hole pairs form tightly Coulomb‐bound excitons with large binding energies. The selection rules for excitonic transitions allow for direct optical generation of a valley‐polarized exciton population using resonant excitation. Here, we investigate the exciton valley dynamics in monolayers of three different TMDCs by means of time‐resolved Kerr rotation at low temperatures. We observe pronounced differences in the valley dynamics of tungsten‐ and molybdenum‐based TMDCs, which are directly related to the opposite order of the conduction‐band spin splitting in these materials.