Düvel Marten, Merboldt Marco, Bange Jan Philipp, Strauch Hannah, Stellbrink Michael, Pierz Klaus, Schumacher Hans Werner, Momeni Davood, Steil Daniel, Jansen G S Matthijs, Steil Sabine, Novko Dino, Mathias Stefan, Reutzel Marcel
I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
Nano Lett. 2022 Jun 22;22(12):4897-4904. doi: 10.1021/acs.nanolett.2c01325. Epub 2022 Jun 1.
Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a strong optical excitation, where the electron and phonon systems can be significantly perturbed and the quasiparticle distributions cannot be described with equilibrium functions. In this work, we use time- and angle-resolved photoelectron spectroscopy to study such far-from-equilibrium many-body interactions for the prototypical material graphene. In accordance with theoretical simulations, we find remarkable transient renormalizations of the quasiparticle self-energy caused by the photoinduced nonequilibrium conditions. These observations can be understood by ultrafast scatterings between nonequilibrium electrons and strongly coupled optical phonons, which signify the crucial role of ultrafast nonequilibrium dynamics on many-body interactions. Our results advance the understanding of many-body physics in extreme conditions, which is important for any endeavor to optically manipulate or create non-equilibrium states of matter.
理解远离平衡的多体相互作用是当前超快凝聚态物理研究的主要目标之一。在此，在强光学激发过程中会出现一种特别有趣但却鲜为人知的情况，即电子和声子系统会受到显著扰动，并且准粒子分布无法用平衡函数来描述。在这项工作中，我们使用时间分辨和角分辨光电子能谱来研究典型材料石墨烯的这种远离平衡的多体相互作用。与理论模拟一致，我们发现光致非平衡条件导致了准粒子自能的显著瞬态重整化。这些观测结果可以通过非平衡电子与强耦合光学声子之间的超快散射来理解，这表明超快非平衡动力学在多体相互作用中起着关键作用。我们的结果推进了对极端条件下多体物理的理解，这对于任何光学操纵或创造物质非平衡态的努力都很重要。
