Direct Observation of High-Temperature Polaronic Behavior In Colossal   Magnetoresistive Manganites
  The temperature dependence of the electronic and atomic structure of the colossal magnetoresistive oxides $La_{1-x}Sr_{x}MnO_{3}$ (x = 0.3, 0.4) has been studied using core and valence level photoemission, x-ray absorption and emission, and extended x-ray absorption fine structure spectroscopy. A dramatic and reversible change of the electronic structure is observed on crossing the Curie temperature, including charge localization and spin moment increase of Mn, together with Jahn-Teller distortions, both signatures of polaron formation. Our data are also consistent with a phase-separation scenario. 
N. Mannella, A. Rosenhahn, C. H. Booth, S. Marchesini, B. S. Mun,   S.-H. Yang, K. Ibrahim, Y. Tomioka, C. S. Fadley