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81.
The question of whether one should speak of a "pairing glue" in the Hubbard and t-J models is basically a question about the dynamics of the pairing interaction. If the dynamics of the pairing interaction arises from virtual states, whose energies correspond to the Mott gap, and give rise to the exchange coupling J, the interaction is instantaneous on the relative time scales of interest. In this case, while one might speak of an "instantaneous glue," this interaction differs from the traditional picture of a retarded pairing interaction. However, as we will show, the dominant contribution to the pairing interaction for both of these models arises from energies reflecting the spectrum seen in the dynamic spin susceptibility. In this case, the basic interaction is retarded, and one speaks of a spin-fluctuation glue which mediates the d-wave pairing. 相似文献
82.
We calculate circulating-current (CC), charge-density-wave, and d-wave-like pairing (d-SC) correlation functions in the three-band Hubbard model for two-leg CuO ladders using the density-matrix renormalization group method and detect a dominant fluctuation in a wide range of parameter values and hole-doping rates. We find that, for model parameters leading to a realistic ground state in the undoped ladder, the CC fluctuations decay faster than the d-SC correlations at least up to a hole doping of 10%. It means that no phase with CC order or dominant CC fluctuations occur at low doping. 相似文献