THE CHEMICAL, NEGATIVE-U APPROACH TO HIGH TEMPERATURE SUPERCONDUCTIVITY

Abstract

Data published over the past year is examined in the light of the on-site negative U modelling proposed earlier. The model emphasizes how one must proceed beyond mixed valence to consider closely the charge transfer fluctuation conditions between the two subsystems. The situation prevailing is an intermediate U situation, being one in proximity to the Mott-Anderson transition. The high level of p-d mixing, in the copper oxide superconductors is seen to favour charge- at the expense of spin-fluctuation mediation. The proposed mixed-valently seeded, disproportionation fluctuation induced pairing requires no modification to pass from discussion of the copper oxide to the bismuth oxide superconductors. The author continues to express his opinion that it is the photoemission data which are primarily being misinterpreted, thereby encouraging misinterpretation of the neutron spin scattering and related experiments, and continuing to attract many theorists towards various spin modellings of HTSC.