Photoexcited Polarons in High Temperature Superconducting Oxides: StructuralDistortion and Low Frequency Polarizability

摘要

Photoinduced absorption measurements have been carried out in the infraredspectral range on a series of 'parent' oxides of high temperature superconductors. In all three materials, the observation of infrared active vibrational (IRAV) modes and an associated electronic transition with common intensity and temperature dependence indicate the formation of self-localized polarons as photogenerated carriers. The photoinduced electronic transition deep in the infrared implies a major shift of oscillator strength leading to a large local polarizability in the vicinity of the polaron.