Van Hove excitons and high- Tc superconductivity

Abstract

I summarize recent work on a model which relates high-temperature superconductivity to ‘excitons’ (short-range charge density wave [CDW] order fluctuations) near the van Hove singularity of the CuO 2 sheets. The model explains the anomalous normal state properties, predicts a pinning of the Fermi energy at a preferred hole concentration, describes the crossover from an antiferromagnetic Mott insulator near half filling to a correlated Fermi liquid in the doped material, and suggests that the superconducting transition is similar to that found in the A15 compounds, but enhanced by effects of lower dimensionality.