EXCITONIC PAIRING IN ELECTRON-DOPED CU-O LAYERS

An excitonic pairing mechanism is proposed for electron-doped Cu-O layers. In contrast with previously proposed models for hole-doped CuO2 and BiO3-based perovskites, the inclusion of the O-O hopping matrix element is relevant in order to obtain pairing. Proximity of Cu and O levels, a gap in the electronic spectrum, and nearest-neighbor Cu-O repulsion are necessary conditions in order to obtain pairing as in the hole-doped case.