ELECTRONIC STATES IN HIGH-TC COPPER-OXIDE SUPERCONDUCTORS .2.

The electronic states in the CuO2-layer have been studied by using the p-d model with the help of the auxiliary boson method for treating the local electronic correlation properly. What have been found are: at sufficiently low temperature the electronic states form coherent bands, whose width and intensity are strongly depending upon number of doped carriers (more significantly for holes than electrons) and the p-d charge transfer energy. In particular, when the number of doped-holes nh is small, a new band form around the Fermi level inside the energy gap and its width and intensity are proportional to nh. Even then the Fermi surface is still determined by the total number of unpaired electrons which are mainly of the localized d-electrons. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.