Šebesta Jakub, Grånäs Oscar
Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 751 20 Sweden.
IT4Innovations, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba, 708 00 Czech Republic.
NPJ Comput Mater. 2025;11(1):219. doi: 10.1038/s41524-025-01708-0. Epub 2025 Jul 7.
The use of ultrashort laser pulses to manipulate properties or investigate a materials response on femtosecond time-scales enables detailed tracking of charge, spin, and lattice degrees of freedom. When pushing the limits of experimental resolution, connection to theoretical modeling becomes increasingly important to infer causality relations. Weyl-semimetals are a particular class of materials of recent focus due to the topological protection of the Weyl-nodes, resulting in a number of fundamentally interesting phenomena. This work provides a first-principles framework based on time-dependent density-functional theory for tracking the distribution of Weyl-nodes in the Brillouin-zone following an excitation by a laser pulse. Investigating the prototype material TaAs, we show that residual shifts in the Weyl-Nodes' position and energy distribution are induced by a photo-excitation within femto-seconds through band-structure renormalization. Further, we provide an analysis of the relaxation pathway of the photoexcited band-structure through lattice vibrations.
使用超短激光脉冲来操纵材料特性或研究材料在飞秒时间尺度上的响应，能够详细追踪电荷、自旋和晶格自由度。在推动实验分辨率极限时，与理论建模的联系对于推断因果关系变得越来越重要。由于外尔节点的拓扑保护，外尔半金属是近来备受关注的一类特殊材料，这导致了许多从根本上来说有趣的现象。这项工作提供了一个基于含时密度泛函理论的第一性原理框架，用于追踪激光脉冲激发后布里渊区中外尔节点的分布。通过研究原型材料砷化钽，我们表明，在飞秒时间内，光激发通过能带结构重整化在外尔节点的位置和能量分布上引起了残余位移。此外，我们还对光激发能带结构通过晶格振动的弛豫路径进行了分析。
