Charge and phase fluctuations in attractive Hubbard model

Using the negative U Hubbard model we analyze normal state properties of a superconductor. In this model there exists a characteristic pairing temperature T-P above a superconducting critical temperature. Below T-P electrons start to form incoherent pairs. The fluctuations in charge and phase are precursors of charge density wave and superconductivity phases depending on band filling. They lead naturally to pseudogap opening in the density of states. (C) 2003 Elsevier Science B.V. All rights reserved.