Superconductivity and phase diagram in a CuO2 monolayer

We recall the van Hove scenario (J. Labbe and J. Bok, Europhys. Lett. 3, 1225 (1987); J. Bouvier and J. Bok, in The Gap Symmetry and Fluctuations in HTSC, J. Bok et al., eds. (Plenum, New York, 1998)) developed since 1987. It explains high T-c, anomalous isotope effect, gap anisotropy etc. We apply this scenario to the superconductive surface layer, obtained by field effect on CaCuO2 by J. H. Schon et al. Preprint (private communication), to be published). We show that the variation of resistivity and Hall effect with temperature in the normal state can be understood by the presence of a van Hove singularity (v.H.s.) in the band structure. The doping by field effect changes the distance between the Fermi level and the v.H.s.