Seiler Hélène, Zahn Daniela, Zacharias Marios, Hildebrandt Patrick-Nigel, Vasileiadis Thomas, Windsor Yoav William, Qi Yingpeng, Carbogno Christian, Draxl Claudia, Ernstorfer Ralph, Caruso Fabio
Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
Department of Mechanical and Materials Science Engineering, Cyprus University of Technology, P.O. Box 50329, 3603 Limassol, Cyprus.
Nano Lett. 2021 Jul 28;21(14):6171-6178. doi: 10.1021/acs.nanolett.1c01786. Epub 2021 Jul 19.
We combine ultrafast electron diffuse scattering experiments and first-principles calculations of the coupled electron-phonon dynamics to provide a detailed momentum-resolved picture of lattice thermalization in black phosphorus. The measurements reveal the emergence of highly anisotropic nonthermal phonon populations persisting for several picoseconds after exciting the electrons with a light pulse. Ultrafast dynamics simulations based on the time-dependent Boltzmann formalism are supplemented by calculations of the structure factor, defining an approach to reproduce the experimental signatures of nonequilibrium structural dynamics. The combination of experiments and theory enables us to identify highly anisotropic electron-phonon scattering processes as the primary driving force of the nonequilibrium lattice dynamics in black phosphorus. Our approach paves the way toward unravelling and controlling microscopic energy flows in two-dimensional materials and van der Waals heterostructures, and may be extended to other nonequilibrium phenomena involving coupled electron-phonon dynamics such as superconductivity, phase transitions, or polaron physics.
我们结合超快电子漫散射实验和电子-声子耦合动力学的第一性原理计算，以提供黑磷中晶格热化的详细动量分辨图像。测量结果揭示了在用光脉冲激发电子后，高度各向异性的非热声子群体持续存在数皮秒的现象。基于含时玻尔兹曼形式的超快动力学模拟辅以结构因子计算，定义了一种重现非平衡结构动力学实验特征的方法。实验与理论相结合使我们能够确定高度各向异性的电子-声子散射过程是黑磷中非平衡晶格动力学的主要驱动力。我们的方法为揭示和控制二维材料及范德华异质结构中的微观能量流动铺平了道路，并且可能扩展到涉及电子-声子耦合动力学的其他非平衡现象，如超导、相变或极化子物理。
