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arXiv 2104.00469cond-mat.str-elcond-mat.mtrl-scicond-mat.othercond-mat.stat-mech
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从低到高电荷密度大极化子液体的基态特征和光谱性质

Ground state features and spectral properties of large polaron liquids from low to high charge densities

C. A. Perroni, G. De Filippis, V. Cataudella

摘要:

为了研究Frohlich模型的基态特征,提出了一种零温下有限密度载流子的变分方法,该方法包括电子-电子和电子-声子相互作用.在大极化子的中间电子-声子耦合制度的特点,该方法考虑到在同一个立足点极化子的形成和极化子-极化子相关性发挥相关的作用,从低到高的电荷密度。包括波动顶部的变分方法,电子光谱函数计算从弱到中间的电子-声子耦合制度找到一个峰-谷-驼峰线的形状。随着电子-声子耦合常数的减小或粒子密度的增加,谱的特征是谱重从非相干峰转移到相干峰。三种不同的密度区域:第一,在低密度下,具有大量非相干光谱权重的单个大极化子的特征不被载流子相互作用改变;第二,在中等密度下,极化子液体显示出从非相干到相干动力学的快速交叉;第三种是在高密度下,其中屏蔽效应是如此突出,以至于系统呈现出常规的金属相。在低到中等密度制度中获得的结果是相关的解释最近的隧道效应和光电发射实验SrTiO 3为基础的系统。

英文摘要:

A new variational approach is proposed at zero temperature for a finite density of charge carriers in order to study ground state features of the Frohlich model including electron-electron and electron-phonon interactions. Within the intermediate electron-phonon coupling regime characteristic of large polarons, the approach takes into account on the same footing polaron formation and polaron-polaron correlations which play a relevant role going from low to high charge densities. Including fluctuations on top of the variational approach, the electronic spectral function is calculated from the weak to the intermediate electron-phonon coupling regime finding a peak-dip-hump line shape. The spectra are characterized by a transfer of spectral weight from the incoherent hump to the coherent peak with decreasing the electron-phonon coupling constant or with increasing the particle density. Three different density regimes stem out: the first, at low densities, where the features of a single large polaron with a substantial incoherent spectral weight are not modified by charge carrier interactions; a second one, at intermediate densities, where the polaronic liquid shows a rapid crossover from incoherent to coherent dynamics; the third one, at high densities, where screening effects are so prominent that the system presents a conventional metallic phase. The results obtained in the low to intermediate density regime turn out to be relevant for the interpretation of recent tunneling and photoemission experiments in SrTiO3-based systems.

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