Electron-phonon coupling in the undoped cuprate YBa2Cu3O6 estimated from Raman and optical conductivity spectra
Electron-phonon coupling in the undoped cuprate YBa2Cu3O6 estimated from Raman and optical conductivity spectra
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DOI：
10.1103/physrevb.98.121104
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发表时间：
2018-09-11
影响因子：
3.7
通讯作者：
Cataudella, V
中科院分区：
文献类型：
--
作者：
Farina, D.;De Filippis, G.;Cataudella, V
实验研究了未掺杂的高温超导母体化合物YBa_2Cu_3 O_6的拉曼响应，并在考虑电子-声子耦合（EPC）的Hubbard-Holstein模型的基础上，给出了双磁振子拉曼峰和光导的统一理论。没有EPC的Hubbard模型可以定性地解释实验观察到的拉曼响应的共振，但只有Hubbard-Holstein模型（i）再现了拉曼光谱的不对称性，（ii）验证了实验可见的双磁振子峰，（iii）预测了电导率中电荷转移带隙下边缘的正确形状和能量。实验与理论的比较给出了EPC强度λ = 0.6。这一结果有力地表明了EPC在高温铜酸盐中的重要作用，为高温铜酸盐的形成机制提供了线索。
We study experimentally the Raman response of the undoped high-T-c parent compound YBa2Cu3O6, and give a unified theory of the two-magnon Raman peak and optical conductivity based on the Hubbard-Holstein model with electron-phonon coupling (EPC). The Hubbard model without EPC can qualitatively account for the experimentally observed resonance of the Raman response, but only the Hubbard-Holstein model (i) reproduces the asymmetry of the Raman spectrum, (ii) validates the experimental visibility of the two-magnon peak, and (iii) predicts the correct shape and energy of the lower edge of the charge transfer gap in optical conductivity. A comparison of experiments with the theory gives the EPC strength lambda = 0.6. This result convincingly indicates the vital role of EPC in high-T-c cuprates, providing a clue to the mechanism of high T-c.