Nature of the pseudogap in cuprate superconductors

The base of the mean-field model that describes the main physical properties of the cuprate superconductors is presented, the single-band Hubbard Hamiltonian of the Mott-states of electrons on CuO-plane. In the present work, the Hamiltonian is diagonalized on a Hartree-Fock base of collinear spins states that leaves fixed the magnetic order on the square sublattices. Adjusted the mean-field in the unit cell to a gap of ~ 2 eV at half-filling and to a maximum value of pseudogap observed of ~ 100 meV, an evaluation of the Hartree-Fock Mott-states in doping with holes and electrons and at the zero absolute temperature is made. It is shown that the mean-field adjust the density of the states at the Fermi level according to the experimental measure. The base of the Hartree-Fock Mott-states prove that the opening of the pseudogap in cuprate superconductors define a phase of low density of states at the Fermi level resulting from Coulomb repulsion on Cu-sites that penalizes two electrons being close to each other. It is also argued that the spontaneous breaking of rotational symmetry in the antiferromagnetic order of the Mott-states leads to the electron pair formation in cuprate superconductors.