Coupled lattice and electronic effects in high-temperature superconductors

Summary form only given. Accumulating data for oxide superconductors which become superconducting at high temperatures continues to point to the strong involvement of (particularly local and dynamic) structural distortion. At the same time, recent band structure calculations suggest that almost crossing electronic bands occur near the Fermi level. It is likely that these two characteristics are closely connected. Here, we : (i) Briefly review some of the evidence for the above characteristics ; (ii) Point out some similarities with perovskite and other martensitic materials, which also show distinctive percursor microstructure; (iii) Present a generalized BCS theory which includes band crossing and hybridization effects, and accounts for a multiphonon pairing mechanism; (iv) Analyze a local polaronic model for dynamic hole motion which can reconcile observations of double well Cu-O bond distributions and nonadiabatic optical spectroscopy features.