标题： PdTe$_{2}$中的新等离激元样态：拉曼散射和记忆函数研究 显示英文标题

标题： New plasmon-like mode in PdTe$_{2}$: Raman scattering and memory function study

摘要： PdTe$_2$是一种 II 型狄拉克半金属，由于其有趣的电子和拓扑性质而引起了广泛关注。 在这里，我们报告了在 10 K 到 300 K 温度范围内 PdTe$_2$的温度依赖拉曼散射研究。我们的研究揭示了在 100 K 以下出现了一个新的未报道的峰，中心位于 250 cm$^{-1}$。 我们认为这个新模式不是声子模式，因为使用密度泛函理论计算的拉曼光谱仅在 85$ cm^{-1}$和 128$cm^{-1}$处有两个强烈的峰。 为了确定这个新峰的起源，我们构建了一个电子耦合到 250$cm^{-1}$处单个等离子体模式的微观模型，并使用记忆函数形式主义，我们得到拉曼弛豫率与频率成线性关系。 我们还对实验数据进行了现象学分析，并计算了频率相关的拉曼弛豫率，结果也发现其与频率呈线性关系。 通过理论和现象学结果的一致性，我们可以确定在低温下观察到的新模式确实是一种等离子体样模式。 此外，两个声子模式的声子频率和线宽在 100 K 以上表现出异常行为。 显示英文摘要

摘要： PdTe$_2$ is a type II Dirac semimetal that has garnered significant attention due to its intriguing electronic and topological properties. Here, we report temperature dependent Raman scattering study of PdTe$_2$ in the temperature range from 10 K to 300 K. Our study reveals emergence of a new unreported peak below 100 K, centered around 250 cm$^{-1}$. We argue that the new mode is not a phonon mode because the Raman spectra calculated using Density Functional Theory shows only two intense peaks at 85 $ cm^{-1}$ and 128 $cm^{-1}$. To ascertain the origin of this new peak, we constructed a microscopic model of electrons coupling to a single plasmon mode at 250 $cm^{-1}$ and using the memory function formalism, we obtained that the Raman relaxation rate is linear in frequency. We also performed phenomenological analysis of the Raman response from the experimental data and computed frequency dependent Raman relaxation rate, which is also found to exhibit a linear dependence on frequency. With the congruence of our theoretical and phenomenological results we could ascertain that the new mode observed at low temperatures is indeed a plasmon-like mode. Further, phonon frequencies and line widths of the two phonon modes exhibit anomalous behavior above 100 K.