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arXiv 2209.13342cond-mat.str-elcond-mat.mtrl-sci
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可果美金属(Cs,Rb)V $_3$ Sb $_5$的有序-无序Peierls不稳定性

Order-disorder Peierls instability in the kagome metal (Cs,Rb)V$_3$Sb$_5$

D. Subires, A. Korshunov, A. H. Said, L. Sánchez, Brenden R. Ortiz, Stephen D. Wilson, A. Bosak, S. Blanco-Canosa

摘要:

可果美金属化合物AV $_3$ Sb $_5$中电荷密度波相位的性质引起了许多问题,它们的起源仍在争论中。在这里,我们结合漫散射(DS)和非弹性X-射线散射(IXS),以确定一个3维(3D)的前体的电荷顺序与传播矢量(0.5 0 0.5),通过一阶相变,它凝聚成一个3D-CDW。准弹性临界散射表明,对扩散前体的主要贡献是弹性中心峰,而没有声子软化。然而,非弹性谱显示在接近相变时爱因斯坦型声子模的小加宽。我们的结果指出,在\textit{L}点的费米面不稳定性的情况下,是有序-无序型的准静态域的临界增长。结果超出了经典的弱耦合Peierls跃迁动力学,并讨论了模型,包括强电子-声子耦合和非绝热性。

英文摘要:

The nature of the charge density wave phases in the kagome metal compound AV$_3$Sb$_5$ has raised many questions and their origin is still under debate. Here, we combine diffuse scattering (DS) and inelastic x-ray scattering (IXS) to identify a 3-dimensional (3D) precursor of the charge order with propagation vector (0.5 0 0.5), which condenses into a 3D-CDW through a first order phase transition. The quasi-elastic critical scattering indicates that the dominant contribution to the diffuse precursor is the elastic central peak without phonon softening. However, the inelastic spectra show a small broadening of the Einstein-type phonon mode on approaching the phase transition. Our results point to the situation where the Fermi surface instability at the \textit{L} point is of order-disorder type with a critical growth of quasi-static domains. The results go beyond the classical weak-coupling Peierls transition dynamics and are discussed within models including strong-electron phonon coupling and non-adiabaticity.

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