| Abstract: | We study the effect of antiferromagnetic (AF) correlations in the three-bandEmery model, with respect to the experimental situation in weakly underdopedand optimally doped BSCCO. In the vicinity of the vH singularity of theconduction band there appears a central peak in the middle of a pseudogap,which is in an antiadiabatic regime, insensitive to the time scale of themechanism responsible for the pseudogap. We find a quantum low-temperatureregime corresponding to experiment, in which the pseudogap is created byzero-point motion of the magnons, as opposed to the usual semiclassicalderivation, where it is due to a divergence of the magnon occupation number.Detailed analysis of the spectral functions along the (π,0)–(π,π)line show significant agreement with experiment, both qualitative and, in theprincipal scales, quantitative. The observed slight approaching-then-recedingof both the wide and narrow peaks with respect to the Fermi energy is alsoreproduced. We conclude that optimally doped BSCCO has a well-developedpseudogap of the order of 1000 K. This is only masked by the narrowantiadiabatic peak, which provides a small energy scale, unrelated to the AFscale, and primarily controlled by the position of the chemical potential. |
