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Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-Tc Cuprates

Youichi Yanase·Kosaku Yamada
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Abstract

The pseudogap phenomena in High-$T_{\rm c}$ cuprates are investigated on the basis of the Hubbard model which includes only the on-site repulsive interaction $U$. We consider the pairing scenario for the pseudogap. The pseudogap arises from the resonance scattering due to the strong superconducting fluctuations. First, the electronic state and the anti-ferromagnetic spin fluctuations are calculated by using the FLEX approximation. The T-matrix (the propagator of the superconducting fluctuations) is calculated by extending the $\acute{\rm E}$liashberg equation. The self-energy due to the superconducting fluctuations is calculated by the T-matrix approximation. The pseudogap is shown in the single particle properties and the magnetic properties by the microscopic calculation. A comprehensive explanation of the doping dependence of the pseudogap is obtained. Furthermore, we apply the theory to the electron-doped cuprates and obtain the consistent results with the recent experiments. Finally, the self-consistent calculation for the spin fluctuations, superconducting fluctuations and the single particle properties are carried out within the FLEX and the self-consistent T-matrix approximations. The calculated superconducting critical temperature $T_{\rm c}$ is remarkably reduced from the results of the mean field (FLEX) calculation. It is shown that the critical temperature decreases with decreasing doping in the under-doped region with large $U$.

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Youichi Yanase, Kosaku Yamada. 2001-03-09. Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-Tc Cuprates. https://doi.org/10.1143/jpsj.70.1659

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