Lattice Instability in High Temperature Superconducting Cuprates and FeAs Systems: Polarons Probed by EXAFS
Figure 7
Schematic local lattice distortions. (a) Various single site deformation schemes involving apical oxygen displacement. (b) correlated deformation schemes with in-plane atomic displacements are schematically illustrated. In case of pseudo JT distortion model (left), oxygen atoms are distorted in a similar fashion with a breezing mode where all Cu–O bonds for each Cu are either elongated or shortened. In the case of type JT distortion, half of Cu–O bonds are either elongated or shortened.
