论文标题
在货车蜜饯填充的电荷密度波金属中的晶格动力学
Lattice dynamics in the charge-density-wave metal at a van-Hove-singularity filling
论文作者
论文摘要
带有宏观占用电子的电荷密度波（CDW）阶会扭曲基础晶格，并通常会导致相关的声子模式的软化。但是，先前的研究表明，自旋 - 旋转过渡并不总是引起相关的声子软化，而是在准二维复合cugeo $ _3 $中应用的中心峰方案。我们概括了有关van-hove-singululity（VHS）二维CDW状态的晶状体 - 动力学研究，并发现CDW订购可以在零频率下以零频率发展中心峰，而相关的声子则经历硬化。 VHS点之间的粒子孔散射导致低能的电荷密度敏感性增加，并且它们与晶格动力学的耦合可在CDW相关的声子模式下诱导两个极点。零频线对应于集体电荷密度和声子耦合模式。高频一个与高温声子模式有关，该模式在达到CDW过渡时硬化。我们的结果可能对最近发现的Kagome Metal $ a $ v $ _3 $ SB $ _5 $（$ a $ = k，rb，cs）具有潜在的影响，在CDW过渡过程中未观察到软声器。
The charge-density-wave (CDW) order with macroscopically occupied electrons distorts the underlying lattice and usually causes the softening of the associated phonon mode. However, previous studies demonstrated that the spin-Peierls transition does not always induce an associated phonon softening, but the central-peak scenario applied in the quasi-one-dimensional compound CuGeO$_3$. We generalize the lattice-dynamics studies on the two-dimensional CDW state at van-Hove-singularity (VHS) filling and find that the CDW ordering could develop a central peak at zero frequency while the associated phonon undergoes hardening. The particle-hole scatterings between VHS points give rise to a low-energy increased charge-density susceptibility, and their coupling to the lattice dynamics induces two poles in the Green function for the CDW-associated phonon mode. The zero-frequency pole corresponds to the collective charge-density and phonon coupling mode. The high-frequency one is related to the high-temperature phonon mode that hardens as reaching the CDW transition. Our result may have the potential implication for the recently discovered Kagome metal $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs) in which no soft phonon is observed during the CDW transition.
