EXAFS study of the local order and structure in Cu doped manganites

We report extended X-ray absorption fine structure measurements at the Mn K edge on (La0.63Ca037) (Mn0.92Cu0.08)O-3 and (La0.25Ca075)(Mn0.92Cu0.08)O-3 samples. We observe that the Cu2+ substitution in these two compounds belonging from the opposite sides of the phase diagram induces two very different effects. In the first case, it weakens ferromagnetic ordering, while in the second one, it does not significantly modify the charge ordering present in the system.