Zhou Faran, Williams Joseph, Sun Shuaishuai, Malliakas Christos D, Kanatzidis Mercouri G, Kemper Alexander F, Ruan Chong-Yu
Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA.
Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
Nat Commun. 2021 Jan 25;12(1):566. doi: 10.1038/s41467-020-20834-5.
Nonequilibrium phase transitions play a pivotal role in broad physical contexts, from condensed matter to cosmology. Tracking the formation of nonequilibrium phases in condensed matter requires a resolution of the long-range cooperativity on ultra-short timescales. Here, we study the spontaneous transformation of a charge-density wave in CeTe from a stripe order into a bi-directional state inaccessible thermodynamically but is induced by intense laser pulses. With ≈100 fs resolution coherent electron diffraction, we capture the entire course of this transformation and show self-organization that defines a nonthermal critical point, unveiling the nonequilibrium energy landscape. We discuss the generation of instabilities by a swift interaction quench that changes the system symmetry preference, and the phase ordering dynamics orchestrated over a nonadiabatic timescale to allow new order parameter fluctuations to gain long-range correlations. Remarkably, the subsequent thermalization locks the remnants of the transient order into longer-lived topological defects for more than 2 ns.
非平衡相变在从凝聚态物质到宇宙学的广泛物理背景中起着关键作用。追踪凝聚态物质中非平衡相的形成需要在超短时间尺度上解决长程协同性问题。在此，我们研究了CeTe中电荷密度波从条纹序自发转变为一种热力学上无法达到但由强激光脉冲诱导的双向状态。通过具有约100飞秒分辨率的相干电子衍射，我们捕捉到了这一转变的全过程，并展示了定义非热临界点的自组织现象，揭示了非平衡能量景观。我们讨论了由快速相互作用猝灭产生的不稳定性，这种猝灭改变了系统对称性偏好，以及在非绝热时间尺度上精心安排的相序动力学，以允许新的序参量涨落获得长程关联。值得注意的是，随后的热化过程将瞬态序的残余锁定在寿命超过2纳秒的长寿命拓扑缺陷中。
