Critical doping in overdoped high-T-c superconductors: a quantum critical point?

Evidence is presented from the scaling of the Knight shift, entropy and tra nsport properties together with the sharp peaking of condensation energy, c ritical currents, superfluid density and a variety of other physical proper ties for the occurrence of a common critical doping point in lightly overdo ped high-T-c, superconductors (HTS). This critical doping lies at the point where the doping-dependent normal-state pseudogap energy, E-g resemblance to a quantum critical point (QCP). A QCP scenario could lead directly to an explanation of the non-Fermi liquid behaviour of the normal-state metallic phase and the overall generic behaviour of the HTSC.