Universal Relationship between Magnetization a N D Changes in the Local Structure in Quasicubic a N D Bilayer Manganites

We extend our previous EXAFS investigations on the relationship between magnetization and local distortions to the bilayer materials La2-2ccSri+2ccMn2 07 and to higher magnetic fields, for quasicubic Lao.7Cao.3Mn03. For each, there is a significant change in the broadening parameter a of the Mn-O pair distribution function (PDF) associated with polaron formation as T is increased through T c . Applying a magnetic field reduces the local distortion of the Ca sample for temperatures near T c . For samples with sharp transitions, there is still a significant change of a with T below T c when the sample is fully magnetized, i.e. distortions are still present and continuing to be removed as T is lowered well below T c . A simple model is presented for the magnetization process.