A modeling of the normal state of the p-doped high-temperaturesuperconductors (HTSC's) is presented. This is achieved starting from a moreconventional metallic phase for optimal- and overdoping and passing via theunderdoped to the insulating state by consecutive orbital selectivecompressibility-incompressibility transitions in terms of sum rules for thecharge response. The modeling is substantiated by corresponding phononcalculations. Extending investigations of the full dispersion and in particularof the strongly doping dependent anomalous phonon modes in LaCuO, which so farunderpin our treatment of the density response of the electrons in the p-dopedHTSC's, gives additional support for the modeling of the electronic state,compares well with recent experimental data and predicts the dispersion for theoverdoped regime. Moreover, phonon densities of states have been calculated andcompared for the insulating, underdoped, optimally doped and overdoped state ofLaCuO. From our modeling of the normal state a consistent picture of thesuperconducting phase also can be extracted qualitatively pointing in theunderdoped regime to a phase ordering transition. On the other hand, themodeling of the optimal and overdoped state is consistent with a quasi-particlepicture with a well defined Fermi surface. Thus, in the latter case a Fermisurface instability with an evolution of pairs of well defined quasiparticlesis possible and can lead to a BCS-type ordering. So, it is tempting tospeculate that optimal $T_C$ in the HTSC's marks a crossover region betweenthese two forms of ordering.
展开▼
