Analysis of characteristic temperatures in high-T-c systems

Using a self-consistent diagrammatic theory of the one-band Hubbard model, we find that three characteristic temperatures T*, T-c*, and T-c may characterize the behavior of high-T-c superconductors. The temperature T* defines the onset of a pseudogap in the density of states and of anomalous normal-state behavior. At T-c* local mean-field-like Cooper-pair formation begins with T-c*<T*. Due to phase fluctuations of the order parameter, global spin-fluctuation-induced dx(2)-y(2)-wave superconductivity occurs only at T-c below T-c*. The suppression of T-c*-->T-c is strong for underdoped systems yielding an optimal doping where T-c is largest. The doping dependence of the penetration depth and the influence of Cooper pairing and antiferromagnetic short-range correlations on photoemission experiments are discussed.