THE INSTABILITY CLOSE TO THE 2D GENERALIZED WIGNER POLARON CRYSTAL DENSITY - A POSSIBLE PAIRING MECHANISM INDICATED BY A KEY EXPERIMENT

Here we show that the metallic phase of Bi2Sr2CaCu2Oy is given by a phase separation. It appears at the phase transition from a Fermi-gas to a Wigner-solid by decreasing the density of a 2D electron gas in the presence of a polaronic electron-lattice interaction. Two phases are in equilibrium: an electron gas confined in a superlattice of quantum stripes and a one-dimensional (1D) incommensurate generalized Wigner charge density wave (CDW) of condensed polarons at T<T* similar to 120K. The 1D confinement of the electron gas gives the non Fermi liquid behavior of the normal state as in ID conductors. The superconducting phase competes with the phase separation below Tc. The pairing mechanism is given by the coupling of polaron pairs with electron pairs. The superconducting energy gap is of the order of the short range polaron-polaron attraction Eb for condensed polarons. The anisotropic gap arises because the electrons in the n=2 subband of the stripe (k(Fy)=2 pi/L, where L is the stripe width) with Fermi wave vector k(F) in the Gamma M direction, k(Fx)= k(Fy), i.e, at 45 degrees degree with the stripe direction, condense at Tc. The resonant confinement of the electron gas in the stripes increases Tc. The superlattice with barrier width W similar to xi(0) quenches the fluctuations in D < 3.