Charge localization by static and dynamic distortions of the MnO6 octahedra in perovskite manganites

We present transport and neutron-diffraction data establishing a clear link between static and dynamic distortions of the MnO6 octahedra and charge mobility in A(1-x)A'(x) MnO3 (A = La or Pr; A' = Ca or Sr). Systematic analysis of the Mn-O bond lengths versus average A-site ionic radius indicates that increasing static coherent MnO6 distortion is associated with increasing insulating behavior and decreasing T-C. Furthermore, we observed a sudden drop of the oxygen thermal parameters at T-C, indicating that static incoherent and dynamic effects are also important.