A theory about high-temperature superconductivity
  We deal with a model for high-temperature superconductivity which maintains that in cuprates electrons running in the copper oxide layers, found in lattice of these materials, form spin-singlet bonds with electrons running in the neighbouring layers. This model reutilizes the BCS scheme, but with the essential difference that the electron pairs are characterized by equal, rather than opposite, momenta as in Cooper pairs. In the present paper, we consider the electron pair formation and a peculiar canonical transformation analogous to the transformation once applied to the theory of pairing correlations in nuclear matter. It is shown that the quasi-particle energy spectrum remains that of the BCS theory, including the linear relationship between forbidden energy gap and critical temperature. The model is also applied to superconductivity of some copperless perovskites of mixed stoichiometry, whose features are of special worth in understanding the mechanism of the phenomenon. The possibility of enhancing critical temperature in cuprates by inserting monovalent ions into the lattice is considered. 
P. Brovetto and V. Maxia