论文标题
低频拉曼响应靠近伊斯丁 - 纽量量子临界点：一种内存矩阵方法
Low frequency Raman response near Ising-nematic quantum critical point: a memory matrix approach
论文作者
论文摘要
最近的拉曼散射实验揭示了$ \ mathrm {fese_ {1-x} s_x} $附近的“准弹性峰”。值得注意的是，峰值发生在亚温度频率下，当温度向QCP降低时，峰值为$ t^α$，$α> 1 $。在这项工作中，我们使用内存矩阵方法对低频拉曼响应进行了理论分析。我们表明，这种准弹性峰与费米表面的依然形成变形的松弛有关。 Specifically, we find that the peak frequency is proportional to $ τ^{-1}χ^{-1}$, where $χ$ is the Ising-nematic thermodynamic susceptibility, and $τ^{-1}$ is the decay rate of the nematic deformation due to an interplay between impurity scattering and electron-electron scattering mediated by critical Ising-nematic fluctuations.我们认为，临界波动在确定观察到的准弹性峰频率的温度依赖性方面起着至关重要的作用。在大于温度的频率下，我们发现拉曼响应与$ω^{1/3} $成比例，并与较早的预测\ cite {klein18a}一致。
Recent Raman scattering experiments have revealed a "quasi-elastic peak" in $\mathrm{FeSe_{1-x}S_x}$ near an Ising-nematic quantum critical point (QCP) \cite{zhang17}. Notably, the peak occurs at sub-temperature frequencies, and softens as $T^α$ when temperature is decreased toward the QCP, with $α>1$. In this work, we present a theoretical analysis of the low-frequency Raman response using a memory matrix approach. We show that such a quasi-elastic peak is associated with the relaxation of an Ising-nematic deformation of the Fermi surface. Specifically, we find that the peak frequency is proportional to $ τ^{-1}χ^{-1}$, where $χ$ is the Ising-nematic thermodynamic susceptibility, and $τ^{-1}$ is the decay rate of the nematic deformation due to an interplay between impurity scattering and electron-electron scattering mediated by critical Ising-nematic fluctuations. We argue that the critical fluctuations play a crucial role in determining the observed temperature dependence of the frequency of the quasi-elastic peak. At frequencies larger than the temperature, we find that the Raman response is proportional to $ω^{1/3}$, consistently with earlier predictions \cite{klein18a}.
