Abstract
The strong infrared (ir) absorption features observed in the copper oxide superconductors are interpreted to be internal electronic and vibrational excitations of a spin-zero charge-transfer complex () formed between a hole and an essentially single paramagnetic square planar Cu unit (). The large magnitude and bimodal frequency dependence of the electronic polarizability implied by the ir data for favors a combined excitonic and "charged phonon" mechanism for superconductivity. It is possible that the carriers of the superconductivity are the highly correlated electrons belonging to the , while the play the role of highly polarizable impurities. The can delocalize as band polarons.
- Received 17 August 1987
DOI:https://doi.org/10.1103/PhysRevB.36.8794
©1987 American Physical Society