论文标题
对MOSI中复杂的非绝热激素动力学的综合研究$ _2 $ n $ _4 $
A comprehensive study of complex non-adiabatic exciton dynamics in MoSi$_2$N$_4$
论文作者
论文摘要
激发子是由结合电子和孔组成的复合玻色子准颗粒，具有许多引人入胜的特性，并且在实际应用中具有巨大的潜力。尽管对激子动力学的实验研究已经发达，但直到两年前，Ab Intible模拟仍保持空缺。在这里，我们将密度功能理论（DFT）和多体扰动理论（MBPT）应用于2D MOSI $ _2 $ n $ _4 $，以研究其与激子相关的物理学以及第一次在理论上和数值上研究其激子相关的物理学和非可吸热超快激发动力学。我们将最终状态的光致发光（PL）光谱作为明亮的激子计算，但其中很多是由深色贡献的，结果与实验性的结果完全匹配。我们还研究了深色涉及的过程，这些过程几乎没有研究，但在许多物理过程中占主导地位，并获得了以下几个主要结果，例如：（i）在整个Brillouin区域（Bz）上的高散射率在10 $^{ - 2} $ fs $^{ - 1} $^{ - 1} $^{ - 1} $^$^$^$^$^$^$^$^$^{-1} $^{-1} $^{-1} $^{-1} $^{-1} $^{-1} （ii）$λ$谷的深色激子的动力学的彻底分析，在几个激子状态下，有效质量为负质量和最高的散射率； （iii）使用实时Boltzmann传输方程（RT-BTE）技术模拟激发后激子的时间分辨演化，其中K/K'Valley的过程激子的过程起着重要作用； （iv）这里还讨论了带有旋转谷锁定的激子动力学，这里还讨论了k/k'Valley的旋转动力学； （v）提出了一种新方法，用于调节激子的非绝热效应，并伴随着手性声子的吸收/发射，通过调整外部圆形极化光的手性。所有结果表明，2D材料Mosi $ _2 $ n $ _4 $是研究Inviton涉及物理并具有良好应用值的理想平台。
Excitons, which are composite boson quasi-particles composed of bound electrons and holes, have many fascinating properties and great potential in practical applications. Though experimental studies on exciton dynamics are well-developed, the ab initio simulation ones still remain vacant until two years ago. Here, we apply the density functional theory (DFT) and many-body perturbation theory (MBPT) on 2D MoSi$_2$N$_4$ to study its exciton-related physics and non-adiabatic ultrafast exciton dynamics theoretically and numerically for the first time. We calculate the photoluminescence (PL) spectra with final states as bright excitons, yet lots of them are contributed by the dark ones, and the results match the experimental ones perfectly. We also study the dark-exciton-involved processes, which were barely studied in the past but dominate in many physical processes, and obtain several main results like: (i) High scattering rates over the whole Brillouin zone (BZ) within the order of magnitude from 10$^{-2}$ fs$^{-1}$ to 10$^{-1}$ fs$^{-1}$; (ii) Thorough analysis for the dynamics of the dark excitons at $Λ$ valley, which have negative effective mass and the highest scattering rate among several exciton states; (iii) Simulate the time-resolved evolution of the excitons after photo-excitation with the real-time Boltzmann transport equation (rt-BTE) techniques, in which process excitons at K/K' valley play an important role; (iv) Exciton dynamics with spin-valley locking at K/K' valley are also discussed here; (v) A new approach is proposed for modulating the non-adiabatic effects for excitons, accompanied by a chiral phonon absorption/emission, by tuning the chirality of the external circularly polarized light. All the results show that the 2D material MoSi$_2$N$_4$ is an ideal platform to study the exciton-involved physics and has great application value.
