Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, 22761, Hamburg, Germany.
Department of Physics, North Carolina State University, Raleigh, 27695-8202, NC, USA.
Nat Commun. 2018 Oct 26;9(1):4452. doi: 10.1038/s41467-018-06991-8.
Nonequilibrium many-body dynamics is becoming a central topic in condensed matter physics. Floquet topological states were suggested to emerge in photodressed bands under periodic laser driving. Here we propose a viable nonequilibrium route without requiring coherent Floquet states to reach the elusive magnetic Weyl semimetallic phase in pyrochlore iridates by ultrafast modification of the effective electron-electron interaction with short laser pulses. Combining ab initio calculations for a time-dependent self-consistent light-reduced Hubbard U and nonequilibrium magnetism simulations for quantum quenches, we find dynamically modified magnetic order giving rise to transiently emerging Weyl cones that can be probed by time- and angle-resolved photoemission spectroscopy. Our work offers a unique and realistic pathway for nonequilibrium materials engineering beyond Floquet physics to create and sustain Weyl semimetals. This may lead to ultrafast, tens-of-femtoseconds switching protocols for light-engineered Berry curvature in combination with ultrafast magnetism.
非平衡多体动力学正成为凝聚态物理的一个核心课题。在周期性激光驱动下，光调制能带中出现了 Floquet 拓扑状态。在这里，我们提出了一种可行的非平衡途径，无需相干 Floquet 态，通过超快改变有效电子-电子相互作用，用短激光脉冲即可在烧绿石型铱酸盐中达到难以捉摸的磁 Weyl 半金属相。通过对含时自洽光还原 Hubbard U 的第一性原理计算和量子猝灭的非平衡磁模拟的结合，我们发现动态修正的磁序导致瞬时出现的 Weyl 锥，其可以通过时间和角度分辨光发射谱进行探测。我们的工作为非平衡材料工程提供了一个独特的、现实的途径，超越了 Floquet 物理，以创造和维持 Weyl 半金属。这可能会导致超快、几十飞秒的切换协议，用于用光工程设计 Berry 曲率，结合超快磁学。
