PHASE-SEPARATION AND CHARGE-DENSITY WAVES - POSSIBLE SOURCES OF NON-FERMI LIQUID BEHAVIOR AND PAIRING IN HIGH-TEMPERATURE SUPERCONDUCTORS

In the absence of a sufficiently singular interaction between the part icles, the Fermi-liquid state is stable above one dimension. To reconc ile this finding with the observed anomalies in the cuprates one is th erefore led to the search for mechanisms giving singular interactions. A recent proposal indicates the cuprates as being close to a charge i nstability, which would drive the system toward phase separation (in t he absence of long-range Coulomb forces between the carriers) or towar d the formation of incommensurate charge-density waves in the more phy sical case of charged carriers. Close to these instabilities strong si ngular and attractive scattering arises between the quasiparticles at the Fermi surface. This scattering would easily account for both the a nomalous behavior of the normal metallic phase and for the strong pair ing mechanism leading to high-temperature superconductivity. The stron g momentum dependence of the singular attraction would also give rise to the (likely) observed unusual d-wave symmetry of the superconductin g order parameter in these systems.