Tencent Meeting ID：664-296-417

会议密码：0305

主 持 人：王亚娴 副研究员

Contact：傅 琦 (fuqi@iphy.ac.cn)

Abstract:
The ultrafast laser excitation of materials leads to strong non-equilibrium dynamics of the electronic and ionic degrees of freedom and generates transient states of matter that differ significantly from the equilibrium properties. In this talk, I will present the study of ultrafast dynamics of coupled electrons and phonons in crystalline solids using the time-dependent Boltzmann equation (TDBE) [1-3]. The approach is firstly applied to photo-excited monolayer MoS2, where the time- and momentum-resolved transient dynamics of electrons and phonons are identified [1]. This non-equilibrium state induced by electron-phonon scattering exists for a few hundred femtoseconds, which then dissipatesthrough phonon-phonon scattering for timescales over 10 ps. Next, the non-equilibrium electron and phonon dynamics from the TDBE simulation are validated through comparison with ultrafast electron diffuse scattering (UEDS) experiments on MoS2 [3] and time-resolved angle-resolved photoemission spectroscopy (tr-ARPES) on SnSe [4]. Finally, I show that electron–phonon and phonon–phonon scatterings also lead to the decay of collective atomic oscillations excited by a laser pulse, known as coherent phonons [5]. First-principles calculations of phonon damping rate of A1g mode of antimony (Sb) and bismuth (Bi) further validate the theoretical derivations.

References
1. Y. Pan, F. Caruso, Nano Lett. 23, 7463 (2023)
2. Y. Pan, F. Caruso, npj 2D Mater. Appl. 8, 42 (2024)
3. Y. Pan, et al, ACS Nano 19, 11381 (2025)
4. Y. Pan, et al, arXiv:2512.15400 (2025)
5. Y. Pan, et al, Phys. Rev. B 112, 245111 (2025)

Brief CV of Dr. Yiming Pan:
潘一铭，现为德国基尔大学理论物理系博士后研究员，2026年在基尔大学获得物理学博士学位。研究方向为非平衡态电子与声子动力学的理论计算。博士期间以第一作者在Nano Letters, ACS Nano, Physical Review B 等国际期刊发表多篇论文， 研究致力于使用实时(real-time) 动力学的方法，结合第一性原理计算的结果，研究激发态下电子和声子的超快动力学行为。该方法能够为飞秒时间分辨实验技术，如超快电子衍射（UEDS）和时间分辨角分辨光电子能谱（TR-ARPES）提供直接的理论参照，有助于深入理解材料超快非平衡动力学的物理机制。