arXiv 1608.025142016-08cond-mat.str-el

关联电子系统的光学响应

Optical response of correlated electron systems

Dmitrii L. Maslov, Andrey V. Chubukov

备注：: as published version
发表信息：: Rep. Prog. Phys. v. 80, 026503 (2017)
DOI：: 10.1088/1361-6633/80/2/026503

摘要：

实验技术的最新进展使得从相关电子材料的光学电导率$σ(Ω, T)$中提取载流子动力学的详细信息成为可能。本文分三个部分，讨论了光学响应的三个方面：1）动量弛豫的作用，2）费米液态金属的光学电导率的$Ω/T$标度，3）非费米液态金属的光学电导率。在第一部分（SEC）。II），我们分析了正常和umklapp散射对电导率的贡献之间的相互作用。在第二部分（Secs。III和IV），我们重新访问的Gurzhi公式的光学散射率，$1/τ(Ω,T)\proptoΩ^2+4π^2 T^2$，并表明，$4π^2$的一个因素是表现的"第一松原频率规则"，其中规定，$1/τ(Ω,T)$必须消失后，解析延续到第一玻色子松原频率。然而，最近的实验表明，在大多数情况下，类似于Gurzhi形式的系数$b$ $1/τ(Ω,T)\proptoΩ^2+bπ^2 T^2$与$b=4$显著不同。我们认为，这种差异可能是由于弹性散射的存在，这降低了$b$低于$4$的值，$b=1$对应于纯弹性散射。在第三部分（SEC）。V），我们考虑了金属在量子相变到自旋态和自旋密度波（SDW）态附近的光学电导。在最后一种情况下，我们专注于"复合"的散射过程，这引起了一个非费米液体行为的光学电导率：$σ'(Ω,T)\propto Ω^{-1/3}$在低频率和$σ'(Ω,T)\propto Ω^{-1}$在较高的频率。我们还讨论了$Ω/T$缩放，并表明同一模型中的$σ'(Ω,T)$与$T^{4/3}Ω^{-5/3}$一样以非费米液体方式缩放。

英文摘要：

Recent progress in experimental techniques has made it possible to extract detailed information on dynamics of carriers in a correlated electron material from its optical conductivity, $σ(Ω, T)$. This review consists of three parts, addressing the following three aspects of optical response: 1) the role of momentum relaxation, 2) $Ω/T$ scaling of the optical conductivity of a Fermi-liquid metal, and 3) optical conductivity of non-Fermi-liquid metals. In the first part (Sec. II), we analyze the interplay between the contributions to the conductivity from normal and umklapp scattering. In the second part (Secs. III and IV), we re-visit the Gurzhi formula for the optical scattering rate, $1/τ(Ω,T)\proptoΩ^2+4π^2 T^2$, and show that a factor of $4π^2$ is the manifestation of the "first-Matsubara-frequency rule", which states that $1/τ(Ω,T)$ must vanish upon analytic continuation to the first boson Matsubara frequency. However, recent experiments show that the coefficient $b$ in the Gurzhi-like form, $1/τ(Ω,T)\proptoΩ^2+bπ^2 T^2$, differs significantly from $b=4$ in most of the cases. We suggest that the discrepancy may be due to the presence of elastic scattering, which decreases the value of $b$ below $4$, with $b=1$ corresponding to purely elastic scattering. In the third part (Sec. V), we consider the optical conductivity of metals near quantum phase transitions to nematic and spin-density-wave (SDW) states. In the last case, we focus on "composite" scattering processes, which give rise to a non-Fermi--liquid behavior of the optical conductivity: $σ'(Ω,T)\propto Ω^{-1/3}$ at low frequencies and $σ'(Ω,T)\propto Ω^{-1}$ at higher frequencies. We also discuss $Ω/T$ scaling and show that $σ'(Ω,T)$ in the same model scales in a non-Fermi-liquid way, as $T^{4/3}Ω^{-5/3}$.

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