Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherence in the Metal Halide Perovskite CH3NH3PbI3
Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherence in the Metal Halide Perovskite CH3NH3PbI3
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DOI：
10.1103/physrevlett.124.157401
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发表时间：
2020-04-16
影响因子：
8.6
通讯作者：
Wang, J.
中科院分区：
文献类型：
--
作者：
Liu, Z.;Vaswani, C.;Wang, J.
我们在CH3NH3PbI3中发现了隐藏的Rashba精细结构，并通过对称选择振子(电子-声子)耦合的振动相干性证明了它的量子控制。在单周期太赫兹泵浦光场的临界阈值以上，拉曼声子模对具有持久相干的中间激子态的调制时间比主要与红外声子耦合的两侧激子态的调制时间长十倍以上。这些振动量子拍子，结合声子周期调制Rashba参数的第一性原理模型，识别了三重激子精细结构分裂，即在两个明亮的暗态之间存在光学禁止的简并暗态，具有类似于3 nm的窄分裂。利用振动量子相干性和对称性，激发了光-钙钛矿型量子控制和自旋分裂带的亚太赫兹“拉什巴工程”，从而实现了终极多功能装置。
We discover hidden Rashba fine structure in CH3NH3PbI3 and demonstrate its quantum control by vibrational coherence through symmetry-selective vibronic (electron-phonon) coupling. Above a critical threshold of a single-cycle terahertz pump field, a Raman phonon mode distinctly modulates the middle excitonic states with persistent coherence for more than ten times longer than the ones on two sides that predominately couple to infrared phonons. These vibronic quantum beats, together with first-principles modeling of phonon periodically modulated Rashba parameters, identify a threefold excitonic fine structure splitting, i.e., optically forbidden, degenerate dark states in between two bright ones with a narrow, similar to 3 nm splitting. Harnessing of vibronic quantum coherence and symmetry inspires light-perovskite quantum control and sub-THz-cycle "Rashba engineering" of spin-split bands for ultimate multifunction device.