Low frequency Raman response near Ising-nematic quantum critical point: a memory matrix approach

Abstract

Recent Raman scattering experiments have revealed a "quasi-elastic peak" in $\mathrm{FeS}{\mathrm{e}}_{1-\mathrm{x}}{\mathrm{S}}_{\mathrm{x}}$ near an Ising-nematic quantum critical point (QCP) \cite{zhang17}. Notably, the peak occurs at sub-temperature frequencies, and softens as $T^{\alpha }$ when temperature is decreased toward the QCP, with $\alpha >1$. 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 ${\tau }^{-1}{\chi }^{-1}$, where $\chi$ is the Ising-nematic thermodynamic susceptibility, and ${\tau }^{-1}$ 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 ${\omega }^{1/3}$, consistently with earlier predictions \cite{klein18a}.

6 pages + 5 figures

References in corpus (9)

• Evidence for an electron nematic phase transition in underdoped iron pnictide superconductors
• An Intrinsic Bond-Centered Electronic Glass with Unidirectional Domains in Underdoped Cuprates
• Low energy effective theory of Fermi surface coupled with U(1) gauge field in 2+1 dimensions
• Enhancement of superconductivity near a nematic quantum critical point
• Are non-Fermi-liquids stable to Cooper pairing?
• The key ingredients of the electronic structure of FeSe
• Suppression of electronic correlations by chemical pressure from FeSe to FeS
• A controlled expansion for certain non-Fermi liquid metals
• Scattering mechanisms and electrical transport near an Ising nematic quantum critical point

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