THE VAN HOVE SINGULARITY AND HIGH-TC SUPERCONDUCTIVITY - THE ROLE OF NANOSCALE DISORDER AND INTERLAYER COUPLING

The van Hove singularity (vHs) model provides a unifying picture for understanding many anomalous features of high-temperature superconductors. The vHs is found to occur very close to the calculated Fermi levels in most high-T(c) cuprates. The large dos peak (the logarithmic singularity is only modestly broadened by interlayer coupling) provides a simple explanation of enhanced superconductivity, but also leads to striking intrinsic disorder, both as the material is doped away from the vHs (potentially nanoscale phase separation), and at the vHs (short-range density wave order).