Electron-boson spectral density function of underdoped Bi2Sr2CaCu2O8+delta and YBa2Cu3O6.50

Article

关键词: HIGH-TEMPERATURE SUPERCONDUCTORS;    STRONG-COUPLED SUPERCONDUCTORS;    TRANSITION-TEMPERATURE;    SPIN EXCITATION;    PSEUDOGAP;    FLUCTUATIONS;    ARCS;   

DOI  :  10.1103/PhysRevB.83.014507

来源: SCIE

【 摘 要 】

We investigate the electron-boson spectral density function, I-2 chi(omega, T), of the CuO2 plane in underdoped Bi2Sr2CaCu2O8+delta (Bi-2212) and underdoped YBa2Cu3O6.50 (Y-123) using the Eliashberg formalism. We apply a new (in-plane) pseudogap model to extract the electron-boson spectral function. For extracting the spectral function we assume that the spectral density function consists of two components: a sharp mode and the broad Millis-Monien-Pines mode. We observe that both the resulting spectral density function and the intensity of the pseudogap show strong temperature dependences: the sharp mode takes the most spectral weight of the function, the peak position of the sharp mode shifts to a lower frequency, and the depth of the pseudogap, 1 - (N) over tilde (0, T), increases as the temperature decreases. We observe also that the total spectral weight of the electron-boson density and the mass enhancement coefficient increase as the temperature decreases. We estimate fictitious (maximum) superconducting transition temperatures, T-c (T), from the extracted spectral functions at various temperatures using a generalized McMillan formula. The estimated (maximum) T-c also shows a strong temperature dependence; it is higher than the actual T-c at all measured temperatures and decreases with decreasing temperature. Since with decreasing temperature the pseudogap gets stronger and the maximum T-c gets lower, we propose that the pseudogap may suppress superconductivity in cuprates.

【 授权许可】

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