Electronic States and Charge Fluctuation on the CuO2-2D Lattice
Electronic states and charge fluctuation on 2D CuO2 lattice with the infinite repulsion on the Cu-sites are investigated with auxiliary boson technique and the l/N expansion method. It is shown that, for a large charge transfer energy, the undoped system is insulating, and that, upon doping, mid- gap states are generated inside the charge transfer gap. Effects of repulsion U pd between Cu- and O-holes on the mid-gap states are then studied. There are two characteristic values of UI pd : One is which makes the undoped system with a small charge transfer energy insulating. The other is Uc pd at which value the charge susceptibility diverges; this implies an instability toward phase separation. The enhanced charge susceptibility may be the driving force of the superconducting instability.
KeywordsHigh Temperature Superconductivity Charge Fluctuation Charge Transfer Energy Charge Susceptibility Undoped System
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- D.S. Hirashima, Y. Ono, K. Miura, T. Matsuura and H. Jichu, to be published.Google Scholar