VAN HOVE SINGULARITIES AND HIGH-Tc SUPERCONDUCTIVITY: A REVIEW

Abstract

This review describes a Fermi liquid picture of high-T c superconductivity. A density-of-states (dos) peak associated with the CuO 2-plane van Hove singularity causes a peak in T c as a function of hole doping. Strong correlation effects drive a Mott transition at half filling. For intermediate doping, the electronic system is unstable against phase separation, with one phase near the insulating state, the other near the T c peak. The large dos leads to competition between superconductivity and structural instability, in analogy with the A15 compounds. The superconductivity appears to be driven by strong electron-phonon coupling, enhanced by fluctuation effects.