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.
Categories: cond-mat.str-el