Jiang Meizhen, Wu Zhen, Yang Qing, Zhang Yuanyuan, Men Yumeng, Jia Tianqing, Sun Zhenrong, Feng Donghai
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.
J Phys Chem Lett. 2022 Mar 24;13(11):2661-2667. doi: 10.1021/acs.jpclett.2c00329. Epub 2022 Mar 17.
Compared with itinerant electrons in monolayer transition-metal dichalcogenides, localized electrons exhibit coherent spin precession in transverse magnetic fields and usually have longer spin relaxation times. Here, we uncover the intrinsic spin dephasing processes of localized electrons whose mechanism remains unclear. Electron spin coherence dynamics are studied by time-resolved Faraday rotation spectroscopy in monolayer MoS, where four subensembles of localized electrons are found with different factor values and inhomogeneous broadening. The spin dephasing rates of all four subensembles include a linearly -dependent part due to -factor inhomogeneity and a -independent part dominated by electron-nuclear hyperfine interaction and/or anisotropic exchange interaction. The hyperfine-induced spin dephasing time is ∼30-40 ns, and the anisotropic exchange-induced spin dephasing time is on the order of subnanoseconds. The findings give insight into the coherent spin dynamics of localized electrons in monolayers and the interaction between the electron spin and its environment.
与单层过渡金属二硫属化物中的巡游电子相比，局域电子在横向磁场中表现出相干自旋进动，并且通常具有更长的自旋弛豫时间。在此，我们揭示了机制尚不清楚的局域电子的本征自旋退相过程。通过时间分辨法拉第旋转光谱研究了单层MoS₂中电子自旋相干动力学，发现了具有不同g因子值和非均匀展宽的四个局域电子子系综。所有四个子系综的自旋退相速率都包括由于g因子不均匀性导致的线性相关部分以及由电子-核超精细相互作用和/或各向异性交换相互作用主导的与g无关的部分。超精细诱导的自旋退相时间约为30 - 40纳秒，各向异性交换诱导的自旋退相时间在亚纳秒量级。这些发现有助于深入了解单层中局域电子的相干自旋动力学以及电子自旋与其环境之间的相互作用。
