Evidence for topological defects in a photoinduced phase transition
Evidence for topological defects in a photoinduced phase transition
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DOI：
10.1038/s41567-018-0311-9
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发表时间：
2018-06
期刊：
影响因子：
19.6
通讯作者：
A. Zong;A. Kogar;Ya‐Qing Bie;T. Rohwer;Changmin Lee;E. Baldini;E. Ergeçen;M. Yilmaz;B. Freelon-B.-F
中科院分区：
文献类型：
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作者：
A. Zong;A. Kogar;Ya‐Qing Bie;T. Rohwer;Changmin Lee;E. Baldini;E. Ergeçen;M. Yilmaz;B. Freelon-B.-F
在强超快激光脉冲激发下，对称破碎基态可以通过不同于热平衡的途径发生非平衡相变。确定这些光诱导相变（PIPTs）的机制一直是凝聚态体系研究中一个长期存在的问题。为此，我们研究了单向电荷密度波（CDW）材料LaTe的光致熔化。使用一套时间分辨探针，我们独立地跟踪了CDW的振幅和相位动态。我们发现CDW振幅的快速（1ps）恢复之后是相位相干性的较慢重建。这种较长的时间尺度是由拓扑缺陷的存在决定的：远程顺序（LRO）被抑制，只有当缺陷湮灭时才能恢复。我们的结果通过识别缺陷的产生作为一种治理机制，为理解其他pipt提供了一个框架。
Upon excitation with an intense ultrafast laser pulse, a symmetry-broken ground state can undergo a non-equilibrium phase transition through pathways dissimilar from those in thermal equilibrium. Determining the mechanism underlying these photo-induced phase transitions (PIPTs) has been a long-standing issue in the study of condensed matter systems. To this end, we investigate the light-induced melting of a unidirectional charge density wave (CDW) material, LaTe. Using a suite of time-resolved probes, we independently track the amplitude and phase dynamics of the CDW. We find that a quick (1ps) recovery of the CDW amplitude is followed by a slower reestablishment of phase coherence. This longer timescale is dictated by the presence of topological defects: long-range order (LRO) is inhibited and is only restored when the defects annihilate. Our results provide a framework for understanding other PIPTs by identifying the generation of defects as a governing mechanism.