Large-bipolaron-liquids in cuprate superconductors

Abstract

Exceptionally displaceable ions, evidenced by huge ratios of materials static to high-frequency dielectric constants, enable short-range electron-phonon interactions to stabilize large planar bipolarons. These large bipolarons are compact and strongly bound. By contrast, very diffuse and weakly bound large bipolarons result without the electron-phonon interactions short-range component. Cuprates superoxygen bipolarons are centered on four inward relaxing oxygen anions circumscribed by four outward relaxing copper cations. Concomitant oxygen to copper charge transfer converts them to spinless Cu1+ cations. The planar d symmetry of superoxygens' groundstate molecular orbital tracks the superoxygens' predominant zeropoint radial vibrations. These large bipolarons distinctive charge transport, absorption, magnetism, local atomic vibrations, condensation into a liquid and subsequent high-temperature superconductivity are consistent with cuprate superconductors' long-established unusual properties.