Weakening of antiferromagnetic correlations by doping in the 2D Hubbard model

The temperature and doping dependence of the 2D Hubbard model is studied in the intermediate coupling regime (U = 4). Strong 2D critical spin fluctuat ions dominating near half-filling are completely destroyed upon about 14% d oping concentration, below which the imaginary part of the self-energy vani shes nearly quadratically in both frequency and temperature, a characterist ic feature for the Fermi liquid. As the doping concentration is increased f rom half-filling, dynamical spin susceptibility shows a change from commens urate to incommensurate structure, leading to a three-peak structure in the spectral function in some region of the Brillouin zone. (C) 1999 Elsevier Science Ltd. All rights reserved.