Relation between charge ordering and local lattice disorder in manganites studied by EXAFS

We report extended X-ray absorption fine structure measurements at the Mn K absorption edge and in a wide temperature range on La0.25Ca0.75MnO3 samples with a charge ordering transition temperature, TCO of the Mn3+ and Mn4+ ions around 225 K. The mean Mn–O distances do not show major changes at the transition; however, our results show the presence of an anomalous local lattice disorder and distortion below TCO, possibly determined by the breaking of the symmetries of the high temperature state, that is the splitting of the Mn–O distances.