Yumoto Go, Hirori Hideki, Sekiguchi Fumiya, Sato Ryota, Saruyama Masaki, Teranishi Toshiharu, Kanemitsu Yoshihiko
Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
Nat Commun. 2021 May 21;12(1):3026. doi: 10.1038/s41467-021-23291-w.
Manipulation of excitons via coherent light-matter interaction is a promising approach for quantum state engineering and ultrafast optical modulation. Various excitation pathways in the excitonic multilevel systems provide controllability more efficient than that in the two-level system. However, these control schemes have been restricted to limited control-light wavelengths and cryogenic temperatures. Here, we report that lead halide perovskites can lift these restrictions owing to their multiband structure induced by strong spin-orbit coupling. Using CsPbBr perovskite nanocrystals, we observe an anomalous enhancement of the exciton energy shift at room temperature with increasing control-light wavelength from the visible to near-infrared region. The enhancement occurs because the interconduction band transitions between spin-orbit split states have large dipole moments and induce a crossover from the two-level optical Stark effect to the three-level Autler-Townes effect. Our finding establishes a basis for efficient coherent optical manipulation of excitons utilizing energy states with large spin-orbit splitting.
通过相干光与物质相互作用来操控激子是一种用于量子态工程和超快光调制的很有前景的方法。激子多能级系统中的各种激发途径提供了比二能级系统更高的可控性。然而，这些控制方案一直局限于有限的控制光波长和低温条件。在此，我们报道卤化铅钙钛矿由于其由强自旋轨道耦合诱导的多能带结构可以消除这些限制。使用CsPbBr钙钛矿纳米晶体，我们观察到在室温下随着控制光波长从可见光区域增加到近红外区域，激子能量位移出现反常增强。这种增强的发生是因为自旋轨道分裂态之间的导带间跃迁具有大的偶极矩，并诱导了从二能级光学斯塔克效应到三能级奥特勒-汤斯效应的转变。我们的发现为利用具有大自旋轨道分裂的能态对激子进行高效相干光学操控奠定了基础。
